Answer:
A) τ = 300 N*m
B) θ = 0.4 rad = 22.9°
Explanation:
Newton's second law:
F = ma has the equivalent for rotation:
τ = I * α Formula (1)
where:
τ : It is the moment applied to the body. (Nxm)
I : it is the moment of inertia of the body with respect to the axis of rotation (kg*m²)
α : It is angular acceleration. (rad/s²)
Data
I = 0.6 kg*m² : moment of inertia of the bat
Angular acceleration of the bat
We apply the equations of circular motion uniformly accelerated :
ωf= ω₀ + α*t Formula (2)
Where:
α : Angular acceleration (rad/s²)
ω₀ : Initial angular speed ( rad/s)
ωf : Final angular speed ( rad
t : time interval (s)
Data
ω₀ = 0
ωf = 20 rad/s
t = 40 ms = 0.04 s
We replace data in the formula (2) :
ωf= ω₀ + α*t
20 = 0 + α* (0.04)
α = 20/ (0.04)
α = 500 rad/s²
Newton's second law to the bat
τ = (0.6 kg*m²) *(500 rad/s²) = 300 (kg*m/s²)* m
τ = 300 N*m
B) Angle through which the bat moved.
We apply the equations of circular motion uniformly accelerated :
ωf²= ω₀ ²+ 2α*θ Formula (3)
Where:
θ : Angle that the body has rotated in a given time interval (rad)
We replace data in the formula (3):
ωf²= ω₀²+ 2α*θ
(20)²= (0)²+ 2(500 )*θ
400 = 1000*θ
θ = 400/1000
θ = 0.4 rad
π rad = 180°
θ = 0.4 rad *(180°/π rad)
θ = 22.9°
A 3.1 g spider is dangling at the end of a silk thread. You can make the spider bounce up and down on the thread by tapping lightly on his feet with a pencil. You soon discover that you can give the spider the largest amplitude on his little bungee cord if you tap exactly once every second.What is the spring constant of the silkthread?
Answer:0.122 N/m
Explanation:
Given
Maximum Amplitude can be obtained when tapped after every second
i.e. Time Period [tex]T=1 s[/tex]
mass of spider [tex]m=3.1 gm[/tex]
and we know
[tex]T\cdot \omega =2\pi [/tex]
where [tex]\omega [/tex]=natural frequency of oscillation
T=time Period
[tex]\omega [/tex] is also given by [tex]\omega =\sqrt{\frac{k}{m}}[/tex]
[tex]1\cdot \sqrt{\frac{k}{m}}=2\pi [/tex]
[tex]1\cdot \sqrt{\frac{k}{3.1\times 10^{-3}}}=2\pi [/tex]
[tex]k=(2\pi )^2\times 3.1\times 10^{-3}[/tex]
[tex]k=0.122 N/m[/tex]
The answer is: [tex]k \approx 0.12 \text{ N/m}.[/tex]
To determine the spring constant of the silk thread, we need to consider the spider's motion as simple harmonic motion (SHM). The frequency of the motion is given by the tapping rate, which is once every second, so the frequency [tex]\( f \)[/tex]is 1 Hz. The mass [tex]\( m \)[/tex]of the spider is 3.1 g, which we need to convert to kilograms for consistency with standard units. Since 1 g = 0.001 kg, we have:
[tex]\[ m = 3.1 \text{ g} = 3.1 \times 10^{-3} \text{ kg} \][/tex]
The period [tex]\( T \)[/tex] of the motion is the reciprocal of the frequency:
[tex]\[ T = \frac{1}{f} = \frac{1}{1 \text{ Hz}} = 1 \text{ s} \][/tex]
For SHM, the period [tex]\( T \)[/tex] is related to the mass[tex]\( m \)[/tex] and the spring constant [tex]\( k \)[/tex] by the following equation:
[tex]\[ T = 2\pi \sqrt{\frac{m}{k}} \][/tex]
Solving for [tex]\( k \),[/tex] we get:
[tex]\[ k = \frac{4\pi^2 m}{T^2} \][/tex]
Substituting the known values for [tex]\( m \), \( T \)[/tex], and using[tex]\( \pi \approx 3.14159 \)[/tex], we have:
[tex]\[ k = \frac{4\pi^2 \times 3.1 \times 10^{-3} \text{ kg}}{(1 \text{ s})^2} \][/tex]
[tex]\[ k = 4\pi^2 \times 3.1 \times 10^{-3} \text{ N/m} \][/tex]
[tex]\[ k = 4 \times (3.14159)^2 \times 3.1 \times 10^{-3} \text{ N/m} \][/tex]
[tex]\[ k \approx 4 \times 9.8696 \times 3.1 \times 10^{-3} \text{ N/m} \][/tex]
[tex]\[ k \approx 120.47 \times 10^{-3} \text{ N/m} \][/tex]
[tex]\[ k \approx 0.12047 \text{ N/m} \][/tex]
Therefore, the spring constant[tex]\( k \)[/tex]of the silk thread is approximately[tex]\( 0.12047 \text{ N/m} \).[/tex]
Imagine that you have obtained spectra for several galaxies and have measured the observed wavelength of a hydrogen emission line that has a rest wavelength of 656.3 nanometers. Here are your results:Galaxy 1: Observed wavelength of hydrogen line is 660.0 nanometers.Galaxy 2: Observed wavelength of hydrogen line is 665.8 nanometers.Galaxy 3: Observed wavelength of hydrogen line is 682.7 nanometers.Calculate the redshift, z, for each of these galaxies.
Answer:
Galaxy 1:
z = 0.0056
Galaxy 2:
z = 0.014
Galaxy 3:
z = 0.040
Explanation:
Spectral lines will be shifted to the blue part of the spectrum¹ if the source of the observed light is moving toward the observer, or to the red part of the spectrum when is moving away from the observer (that is known as the Doppler effect). The source in this particular case is represented for each of the galaxies of interest.
Hence, the redshift represents this shift of the spectral lines to red part in the spectrum of a galaxy or any object which is moving away. That is a direct confirmation of how the universe is in an expanding accelerated motion.
The redshift can be defined in analytic way by means of the Doppler velocity:
[tex]v = c\frac{\Delta \lambda}{\lambda_{0}}[/tex] (1)
Where [tex]\Delta \lambda[/tex] is the wavelength shift, [tex]\lambda_{0}[/tex] is the wavelength at rest, v is the velocity of the source and c is the speed of light.
[tex]v = c(\frac{\lambda_{measured}-\lambda_{0}}{\lambda_{0}})[/tex]
[tex]\frac{v}{c} = \frac{\lambda_{measured}-\lambda_{0}}{\lambda_{0}}[/tex]
[tex]z = \frac{\lambda_{measured}-\lambda_{0}}{\lambda_{0}}[/tex] (2)
Where z is the redshift.
For the case of Galaxy 1:
Where [tex]\lambda_{measured} = 660.0 nm[/tex] and [tex]\lambda_{0} = 656.3 nm[/tex].
[tex]z = \frac{\lambda_{measured}-\lambda_{0}}{\lambda_{0}}[/tex]
[tex]z = (\frac{660.0 nm - 656.3 nm}{656.3 nm})[/tex]
[tex]z = 0.0056[/tex]
For the case of Galaxy 2:
Where [tex]\lambda_{measured} = 665.8 nm[/tex] and [tex]\lambda_{0} = 656.3 nm[/tex].
[tex]z = \frac{665.8 nm - 656.3 nm}{656.3 nm}[/tex]
[tex]z = 0.014[/tex]
For the case of Galaxy 3:
Where [tex]\lambda_{measured} = 682.7 nm[/tex] and [tex]\lambda_{0} = 656.3 nm[/tex].
[tex]z = \frac{682.7 nm - 656.3 nm}{656.3 nm}[/tex]
[tex]z = 0.040[/tex]
Key terms:
¹Spectrum: Decomposition of light in its characteristic colors (wavelengths).
Glycerin (C3H8O3) is a nonvolatile liquid. What is the vapor pressure of a solution made by adding 154 g of glycerin to 316 mL of H2O at 40.0°C? The vapor pressure of pure water at 40.0°C is 55.32 torr and its density is 0.992 g/cm3.
Answer:
[tex]P_{sol}=50.4\ mm.Hg[/tex]
Explanation:
According to given:
molecular mass of glycerin, [tex]M_g=3\times 12+8+3\times 16=92\ g.mol^{-1}[/tex]molecular mass of water, [tex]M_w=2+16=18\ g.mol^{-1}[/tex]∵Density of water is [tex]0.992\ g.cm^{-3}= 0.992\ g.mL^{-1}[/tex]∴mass of water in 316 mL, [tex]m_w=316\times 0.992=313.5 g[/tex]mass of glycerin, [tex]m_g=154\ g[/tex]pressure of mixture, [tex]P_x=55.32\ torr= 55.32\ mm.Hg[/tex]temperature of mixture, [tex]T_x=40^{\circ}C[/tex]Upon the formation of solution the vapour pressure will be reduced since we have one component of solution as non-volatile.
moles of water in the given quantity:
[tex]n_w=\frac{m_w}{M_w}[/tex]
[tex]n_w=\frac{313.5}{18}[/tex]
[tex]n_w=17.42 moles[/tex]
moles of glycerin in the given quantity:
[tex]n_g=\frac{m_g}{M_g}[/tex]
[tex]n_g=\frac{154}{92}[/tex]
[tex]n_g=1.674 moles[/tex]
Now the mole fraction of water:
[tex]X_w=\frac{n_w}{n_w+n_g}[/tex]
[tex]X_w=\frac{17.42}{17.42+1.674}[/tex]
[tex]X_w=0.912[/tex]
Since glycerin is non-volatile in nature so the vapor pressure of the resulting solution will be due to water only.
[tex]\therefore P_{sol}=X_w\times P_x[/tex]
[tex]\therefore P_{sol}=0.912\times 55.32[/tex]
[tex]P_{sol}=50.4\ mm.Hg[/tex]
A camera gives a proper exposure when set to a shutter speed of 1/250 s at f-number F8.0. The photographer wants to change the shutter speed to 1/1000 s to prevent motion blur. To maintain proper exposure, she should also change the f-number to...? The answer is F4.0.
Answer:
F4.0
Explanation:
To obtain a shutter speed of 1/1000 s to avoid any blur motion the f-number should be changed to F4.0 because the light intensity goes up by a factor of 2 when the f-number is decreased by the square root of 2.
A conductor bent into a semicircle of total length 3.88 m is placed in a 2.0 T magnetic field perpendicular to the plane of the semicircle. What is the magnitude of the total force on the conductor if a 5.02 A current passes through it?
Answer:
Magnetic force, F = 38.95 N
Explanation:
Given that,
Length of the conductor, L = 3.88 m
Magnetic field, B = 2 T
Current flowing in the conductor, I = 5.02 A
The magnetic field perpendicular to the plane of the semicircle. The angle between the magnetic field and the plane is 90 degrees. The expression for the magnetic force is given by:
[tex]F=ILB\ sin\theta[/tex]
[tex]F=ILB[/tex]
[tex]F=5.02\times 3.88\times 2[/tex]
F = 38.95 N
So, the magnitude of the total force acting on the conductor in the magnetic field is 38.95 N. Hence, this is the required solution.
A car drives at steady speed around a perfectly circular track.
a. The car's acceleration is zero.
b. Both the acceleration and net force on the car point outward.
c. The net force on the car is zero.
d. If there is no friction, the acceleration is outward.
e. Both the acceleration and net force on the car point inward.
Answer:
e. Both the acceleration and net force on the car point inward.
Explanation:
If no net force acts on the car, the car must drive in a straight line, at constant speed.
As the acceleration is defined as the rate of change of the velocity vector, this means that it can produce either a change in the magnitude of the velocity (the speed) or in the direction.
In order to the car can follow a circular trajectory, it must be subjected to an acceleration, that must go inward, trying to take the car towards the center of the circle.
The net force that causes this acceleration, aims inward, and is called the centripetal force.
It is not a different type of force, it can be a friction force, a tension force, a normal force, etc., as needed.
The net force on a car driving around a circular track at steady speed is zero, resulting in zero acceleration. Hence, the correct option is c.
The net force on the car is zero. When a car drives at a steady speed around a circular track, the centripetal force required to keep it moving in a circle balances out the outward inertia. Therefore, there is no net force on the car. This leads to zero acceleration (choice c).
One of the most accurate atomic clocks is the hydrogen maser. This devise uses excited hydrogen molecules to duplicate 1.420-GHz microwave photons. In the maser, the molecules have only two states: the upper maser state and the lower maser state (which is actually the ground state). To keep the maser operating, an electromagnetic system constantly adds excited state hydrogen molecules to the maser and a pump constantly removes ground-state hydrogen molecules from the maser. Why does the maser require a steady supply of new excited state molecules?
Answer:
we have to have many atomicen the excited state and remove all possible atoms from the base state to maintain the population difference between the states and to maintain the emission.
Explanation:
In quantum mechanics the stable state of matter is the fundamental state (lower maser) where the molecular will accumulate, we must have a mechanism to remove the molecules from this state and raise them to the higher state. In the upper state, due to the uncertainty principle, they can only this certain time before decaying. In this process of decay we have two types of emissions: spontaneous and stimulated.
With the spontanease emission they produce the first photons, which stimulate the stimulated emission, which is proportional to the number of atoms in the excited state (higher maser) whereby the more atoms there in this state the emission stimulated in much greater than the spontaneous one that It is approximately constant. The above is the beginning of all lasers.
In summary, we have to have many atomicen the excited state and remove all possible atoms from the base state to maintain the population difference between the states and to maintain the emission.
Two masses sit at the top of two frictionless inclined planes that have different angles. Which mass gets to the bottom first?
Answer:
Explanation:
Let the two inclined planes having angle of inclinations α and β.
The acceleration along the inclined plane acting on the body is gSinα and gSinβ.
If α > β
So, g Sinα > g Sinβ
So, more the inclination of the plane more be the acceleration of body and hence the time taken is less.
So, the body kept on the inclined whose inclination is more reaches at the bottom first.
The mass sitting on the plane inclined to a greater angle to the horizontal will reach the bottom first because it will experience greater acceleration.
Let the angle of inclination of the first mass to the horizontal = θLet the angle of inclination of the second mass to the horizontal = β
The net horizontal force on the masses is calculated as follows;
[tex]\Sigma F_x = 0\\\\mgsin(\theta) = ma\\\\gsin(\theta) = a\ \ \ or \ \ \ \\\\gsin(\beta ) = a[/tex]
Assuming the value of the angles of inclination of the plane is the following;
θ = 60⁰ and β = 30⁰a = gsin(60) = 0.866g
a = gsin(30) = 0.5g
Thus, we can conclude that the mass sitting on the plane inclined to a greater angle to the horizontal will reach the bottom first because it will experience greater acceleration.
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Hoover Dam on the Colorado River is the highest dam in the United States at 221m, with a power output of 680 MW. The dam generates electricity by flowing water down to a point 150 m below the stop, at an average flow rate of 650 m3/s.
Part (a) Calculate the power in this flow in watts.
Answer:
Power = 9.75 ×10^8[tex]\frac{kgm^2}{s^3}[/tex]
Explanation:
Power is rate of change of energy.Here gravitational energy is transferred to kinetic energy of water at a definite rate.For one second 650m^3 of water flows out down to 150m oh depth.
So, the energy at a height of 150m is transformed to kinetic energy.
for a second,
650m^3 of water flows down ⇒ (1000kg/m^3 × 650m^3) = 6.5×10^5kg of warer flos down.
The total gravitational potential energy stored in water is
= mass of water × height× gravity
= 6.5 ×10^5 × 150 × 10 = 9.75 ×10^8[tex]\frac{kgm^2}{s^2}[/tex]
As it is transformed in a second it is also equal to Power.
Answer:
power = 1407.77 MW
Explanation:
The basic principle of a hydro electric station is the conversion of potential energy to electrical energy. Here, water is allowed to fall from a height which will increase its the kinetic energy. This high speed flowing water is used to rotate the shaft of a turbine which will in turn produce electrical energy.
So here,
power = rate of change of potential energy with respect to time
power = [tex]\frac{d(mgh)}{dt}[/tex]
where,
m = mass of water
g = acceleration due to gravity
h = height through which the water falls
here h and g are constants ( h is the total height through which the water falls and it doesn't change with time). Therefore we can take them out of differentiation.
thus,
power = gh[tex]\frac{d(m)}{dt}[/tex]
now,
m = ρV
where,
ρ = density
V = volume
substituting this in the above equation we get,
power = gh[tex]\frac{d(ρV)}{dt}[/tex]
again ρ is a constant. Thus,
power = ρgh[tex]\frac{d(V)}{dt}[/tex]
Given that,
h = 221 m
[tex]\frac{d(V)}{dt}[/tex] = 650 [tex]m^{3}[/tex]/s
g = 9.8 m/[tex]s^{2}[/tex]
ρ = 1000 kg/[tex]m^{3}[/tex]
substituting these values in the above equation
power = 1000 x 9.8 x 221 x 650
power = 1407.77 MW
A rope is tied to a tree 4.5 feet from the ground and then run through a pulley hooked to a vehicle 33 feet from the tree. If a person stands at the tree and pulls ten feet of the rope (after all slack is taken up) how far will the vehicle move?
If a person pulls ten feet of the rope tied to a vehicle through a pulley, the vehicle will move the same distance, which is ten feet assuming ideal conditions with no slack or stretch in the system.
Explanation:The question is asking about how far a vehicle moves when a rope attached to it and run through a pulley is pulled a certain distance. This scenario can be understood using the principles of distance and leverage as applied in physics. When you pull a rope through a pulley, the movement or distance covered by the object attached to the rope is equivalent to the length of the rope pulled.
In this case, if a person pulls ten feet of the rope, the vehicle will also move ten feet. It's important to note that this is applicable under ideal conditions where the rope and pulley do not stretch or bend and the there is no slack in the system.
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A 77.0-kg ice hockey goalie, originally at rest, catches a 0.125-kg hockey puck slapped at him at a velocity of 37.5m/s. Suppose the goalie and the ice puck have an elastic collision and the puck is reflected back in the direction from which it came.What would the final velocities of the goalie and the puck be in this case? Assume that the collision is completely elastic.
A. v goalie = _____ m / s
B. v puck = ______ m / s
Answer
given,
Mass of ice hockey goalie = (M) = 77 Kg
mass of pluck = (m) = 0.125 Kg
velocity of pluck (u₁)= 37.5 m/s
u₂ = 0
Let v₁ and v₂ are the velocity of m₁ and m₂
final velocities are
[tex]v_1 = \dfrac{M-m}{M+m}u_2 + \dfrac{2m}{M+m}u_1[/tex]
v_1 is velocity of goalie
[tex]v_2= \dfrac{m-M}{m+M}u_1 + \dfrac{2M}{m+M}u_2[/tex]
v_2 is velocity of puck
now,
a) for goalie
[tex]v_1 = \dfrac{M-m}{M+m}u_2 + \dfrac{2m}{M+m}u_1[/tex]
[tex]v_1 = \dfrac{77-0.125}{77+0.125}(0) + \dfrac{2(0.170)}{77+0.125}(37.5)[/tex]
[tex]v_1 =0.165\ m/s[/tex]
b) for pluck
[tex]v_2= \dfrac{m-M}{m+M}u_1 + \dfrac{2M}{m+M}u_2[/tex]
[tex]v_2= \dfrac{0.125-77}{77+0.125}(37.5)+ \dfrac{2\times 77}{77+0.125}(0)[/tex]
[tex]v_2= -37.38\ m/s[/tex]
A system contains a perfectly elastic spring, with an unstretched length of 20 cm and a spring constant of 4 N/cm.
(a) How much elastic potential energy does the spring contribute when its length is 23 cm?
(b) How much more potential energy does it contribute if its length increases to 26 cm?
Answer:
a) When its length is 23 cm, the elastic potential energy of the spring is
0.18 J
b) When the stretched length doubles, the potential energy increases by a factor of four to 0.72 J
Explanation:
Hi there!
a) The elastic potential energy (EPE) is calculated using the following equation:
EPE = 1/2 · k · x²
Where:
k = spring constant.
x = stretched lenght.
Let´s calculate the elastic potential energy of the spring when it is stretched 3 cm (0.03 m).
First, let´s convert the spring constant units into N/m:
4 N/cm · 100 cm/m = 400 N/m
EPE = 1/2 · 400 N/m · (0.03 m)²
EPE = 0.18 J
When its length is 23 cm, the elastic potential energy of the spring is 0.18 J
b) Now let´s calculate the elastic potential energy when the spring is stretched 0.06 m:
EPE = 1/2 · 400 N/m · (0.06 m)²
EPE = 0.72 J
When the stretched length doubles, the potential energy increases by a factor of four to 0.72 J
A conducting sphere of radius r1= 0.38m has a total charge of Q=.75 uC. A second uncharged conducting sphere of radius r2= 0.28m is then connected to the first by a thin conducting wire. The spheres are separated by a very large distance to their size. What is the total charge on sphere two, Q2, in C?
Answer:
The Q₂ is 0.318 μC
Explanation:
The charge flows is the same on both, then:
[tex]V_{1} =\frac{kQ_{1} }{r_{1} } \\V_{2} =\frac{kQ_{2} }{r_{2} } \\Q_{2} =Q-Q_{1} \\\frac{kQ_{1} }{r_{1} } =\frac{k*(Q-Q_{1}) }{r_{2} } \\Q_{1} =\frac{\frac{Q}{r_{2} } }{(1/r_{1})+(1/r_{2}) }[/tex]
But:
[tex]\frac{1}{r_{1} } +\frac{1}{r_{2} }=\frac{1}{0.38} +\frac{1}{0.28} =6.2[/tex]
Q = = 0.75 μC
Replacing:
[tex]Q_{1} =\frac{\frac{0.75}{0.28} }{6.2} =0.432\mu C[/tex]
The Q₂ is equal:
Q₂ = 0.75 - 0.432 = 0.318 μC
The second conducting sphere, once connected and then disconnected from the first, ends up with the same charge as the first sphere, 0.75 µC or 0.75 x 10^-6 C.
Explanation:When two conducting spheres are connected by a thin conducting wire, the charge distributes itself evenly across both spheres, assuming both spheres are identical in size. In the case of spheres with different radii, the amount of charge on each sphere once they are separated again will still be proportional to the original amount. Since the two spheres in the question are described to be separated by a large distance relative to their size, the thin wire connecting them would create an equipotential surface, allowing the charge to redistribute.
The total charge Q is conserved in the system, thus the charge on the second sphere Q2 after disconnecting the wire would be the same as the initial total charge Q since it was not charged before. Therefore, the total charge on sphere two, Q2, will also be 0.75 μC or 0.75 x 10^{-6} C.
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A playground merry-go-round has radius 2.80 m and moment of inertia 2400 kg⋅m2 about a vertical axle through its center, and it turns with negligible friction.A child applies an 20.0 N force tangentially to the edge of the merry-go-round for 25.0 s . If the merry-go-round is initially at rest, what is its angular speed after this 25.0 s interval?
Answer:
[tex]\omega_f = 0.602\ rad/s[/tex]
Explanation:
given,
radius of merry- go- round = 2.80 m
moment of inertia = I = 2400 kg⋅m²
child apply force tangentially = 20 N
for time = 25 s
angular speed after 25 speed = ?
initial angular speed of the merry go round = 0 rad/s
we know,
torque = I α.............(1)
α is angular acceleration
and also
τ = F.r........................(2)
computing equation (1) and (2)
F . r = I α
[tex]\alpha = \dfrac{\omega_f - \omega_i}{t}[/tex]
[tex]F . r =I \times \dfrac{\omega_f - \omega_i}{t}[/tex]
[tex]20 \times 2.89 =2400\times \dfrac{\omega_f -0}{25}[/tex]
[tex]\omega_f = 0.602\ rad/s[/tex]
the angular speed of merry-go-round after 25 second is equal to [tex]\omega_f = 0.602\ rad/s[/tex]
According to Little's Law, which of the following can reduce the number of skiers waiting in line to ride a chairlift at a ski resort? a. Using a process layout b. Decreasing the chairlift's bandwidth c. Increasing the chairlift's throughput rate d. Increasing the skiers' average flow time e. Decreasing the skiers' average flow time
Answer:
C. Increasing the chairlift's throughput rate.
Explanation:
The throughput rate is the rate at which a product (the skiers) are moved through a process (Riding the chairlift).
The objective lens and the eyepiece lens of a telescope are 1.0 m apart. The telescope has an angular magnification of 45. Part A Find the focal length of the eyepiece. Express your answer with the appropriate units. fef e = nothing nothing Request Answer Part B Find the focal length of the objective. Express your answer with the appropriate units. fof o = nothing nothing
Answer:
(A) 0.0217 m
(B) 0.9765 m
Explanation:
Distance between the objective lens and the eye piece, d = 1.0 m
Angular magnification, m = 45
Now,
(A) To calculate the focal length of objective:
[tex]\frac{f_{o}}{f_{e}} = 45[/tex]
where
[tex]f_{ob}[/tex] = focal length of object
[tex]f_{ey}[/tex] = focal length of eye piece
Thus
[tex]f_{ob} = 45f_{ey}[/tex] (1)
[tex]f_{ob} + f_{ey} = d[/tex]
[tex]f_{ob} + f_{ey} = 1.0[/tex]
From eqn (1):
[tex]45f_{ey} + f_{ey} = 1.0[/tex]
[tex]f_{ey} = \frac{1.0}{46} = 0.0217\ m[/tex]
(B) To calculate the focal length of eye piece:
From eqn (1):
[tex]f_{ob} = 45\times 0.0217 = 0.9765\ m[/tex]
Based on the data provided, the focal length of the eyepiece is 2 cm while the focal length of the objective is 98 cm.
What is the focal length of a lens?The focal length of a lens is the distance between the principal focus and the centre of the lens.
Magnification of a lens is given by the formula below:
magnification = Fo/Fewhere:
Fo is focal length of objective lensFe is focal length of eyepieceFrom the data provided;
angular magnification = 45
Fo/Fe = 45
Fo = 45 × Fe
Also;
Fe + Fo = 1.0
Fe = 1 - Fo
Substituting in the previous equation
Fo = 45 × (1 - Fo)
Fo = 45 - 45Fo
46Fo = 45
Fo = 45/46
Fo = 0.98 m = 98 cm
From Fe = 1 - Fo
Fe = 1 - 0.98
Fe = 0.02 m = 2 cm
Therefore, the focal length of the eyepiece is 2 cm while the focal length of the objective is 98 cm.
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A clear sheet of polaroid is placed on top of a similar sheet so that their polarizing axes make an angle of 30° with each other. The ratio of the intensity of emerging light to incident unpolarized light is:
Answer:
[tex]\dfrac{I}{I_0}=\dfrac{3}{8}[/tex]
Explanation:
Given that
Angle ,θ = 30°
From Malus law,Intensity given as
[tex]I=\dfrac{I_0}{2}cos^2\theta[/tex]
Io=Intensity of unpolarized light
I=Intensity of emerging light
Now by putting the value of angle
[tex]I=\dfrac{I_0}{2}cos^2\theta[/tex]
[tex]I=\dfrac{I_0}{2}cos^230^{\circ}[/tex]
We know that
[tex]cos30^{\circ}=\dfrac{\sqrt{3}}{2}[/tex]
[tex]I=\dfrac{I_0}{2}\times \dfrac{3}{4}[/tex]
[tex]\dfrac{I}{I_0}=\dfrac{3}{8}[/tex]
Therefore ratio will be [tex]\dfrac{3}{8}[/tex]
Answer:
Ratio of the intensity of emerging light[tex]$\frac{I}{I_{0}}=\frac{3}{8}$[/tex]
Explanation:
Given:
Angle,[tex]$\theta=30^{\circ}$[/tex]
Step 1:
According to Malus law,
Intensity,
[tex]$I=\frac{I_{0}}{2} \cos ^{2} \theta$[/tex]
[tex]l_{0} =[/tex]Intensity of unpolarized light
[tex]l=[/tex]Intensity of emerging light
Step 2:
Put the value of angle
[tex]$I=\frac{I_{0}}{2} \cos ^{2} \theta$[/tex]
[tex]$I=\frac{I_{0}}{2} \cos ^{2} 30^{\circ}$[/tex]
We know,
[tex]$\cos 30^{\circ}=\frac{\sqrt{3}}{2}$[/tex]
[tex]$I=\frac{I_{0}}{2} \times \frac{3}{4}$[/tex]
So, the intensity of the ratio
[tex]$\frac{I}{I_{0}}=\frac{3}{8}$[/tex]
Therefore, the ratio of the intensity of light is [tex]$\frac{3}{8}$[/tex]
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A 3 kg steel ball falls down vertically and strikes a floor with a speed of 12 m/s. It bounces off upward with the same speed. If the ball is in contact with the floor for 0.12 s, what is the magnitude of the average force exerted on the ball by the floor?
Answer:
600N
Explanation:
If the ball bounces off upward with the same speed, the velocities before and after are equal and in opposite directions. That means the floor must have caused a momentum impact to change its direction.
By the law of momentum conservation:
[tex]mv + \Delta P_f = mV[/tex]
where m = 3 kg is the ball mass. v = -12 m/s is the velocity right before the impact. V = 12m/s is the velocity right after the impact. ΔP_f is the momentum caused by the floor.
[tex]\Delta P_f = m(V-v) = 3(12 - (-12)) = 3*24 = 72kgm/s[/tex]
Then the average force exerted during the 0.12s impact is
[tex]F = \frac{\Delta P_f}{\Delta t} = \frac{72}{0.12} = 600N[/tex]
A 0.15 kg baseball is hit by a baseball bat. Right before it is hit, the ball’s speed is 30 m/s, and right after it is hit, the ball’s speed is 50 m/s in the opposite direction. What is the magnitude of the net impulse that is applied to the ball?
10.5 kg?m/sA. 4.5 kg?m/sB. 12.0 kg?m/sC. 7.5 kg?m/sD. 3.0 kg?m/s
Answer:
Impulse will be 12 kgm/sec
So option (b) will be correct option
Explanation:
We have given mass of the baseball m = 0.15 kg
Ball speed before hit [tex]v_1=30m/sec[/tex]
Ball speed after hitting [tex]v_2=-50m/sec[/tex] ( negative direction due to opposite direction )
We have to find the impulse
We know that impulse is equal; to the change in momentum
So change in momentum = [tex]m(v_1-v_2)=0.15(30-(-50))=0.15\times 80=12kgm/sec[/tex]
So option (b) will be correct option
The relative kinetic energy loss through a process is defined as ΔΚ Δκ. к, relatine a. Rewrite part (a) in terms of the mass ratio (m, mincoming/mstationary) due to a completely inelastic collision where the second objects is at rest? b. If I want a system that loses 25% of the kinetic energy after a completely inelastic collision, what should the mass ratio be? c. If I want a system that loses 75% of the kinetic energy after a completely inelastic collision, what should the mass ratio be?
Answer:
Explanation:
Let mass m₁ is colliding in-elastically with stationary mass m₂ with velocity v₁ . Let v₂ be their conjugate velocity after collision .
Initial KE =1/2 m₁ v₁²
Final KE = 1/2 ( m₁ + m₂ ) v₂²
from conservation of momentum
v₂ = m₁v₁ / ( m₁ + m₂)
Final KE = 1/2 ( m₁ + m₂ ) m₁²v₁² / ( m₁ + m₂ )²
= 1/2 m₁²v₁² / ( m₁ + m₂ )
Loss of KE = ΔK
= 1/2 m₁ v₁² - 1/2 m₁²v₁² / ( m₁ + m₂ )
= 1/2 m₁ v₁² ( 1 - m₁ / m₁ + m₂ )
= 1/2 m₁ v₁² m₂ / (m₁ + m₂ )
ΔK / K= m₂ / (m₁ + m₂ )
= β / (1 + β)
where β = m₂ / m₁
b )
If ΔK / K = .25
.25 = β / (1 + β)
β = 1/3
c )
If
ΔK / K = .75
.75 = β / (1 + β)
β = 3
8. A gas is contained in a horizontal piston-cylinder apparatus at a pressure of 350 kPa and a volume of 0.02 m3 . Determine the work done by the piston on the gas if the cylinder volume is increased to 0.15 m3 through heating. Assume the pressure of the
Answer:
45500 J
Explanation:
Pressure, P =350 kPa = 350 x 1000 Pa
V1 = 0.02 m^3
V2 = 0.15 m^3
Work done by the piston
W = Pressure x increase in volume
W = P x (V2 - V1)
W = 350 x 1000 (0.15 - 0.02)
W = 45500 J
Thus, the work done is 45500 J.
Final answer:
The piston performs 45500 Joules of work on the gas when the volume of the gas in the piston-cylinder apparatus increases from 0.02 m³ to 0.15 m³ at a constant pressure of 350 kPa.
Explanation:
To determine the work done by the piston on the gas when the cylinder volume increases from 0.02 m³ to 0.15 m³ at a constant pressure of 350 kPa, we can use the formula for work done during a quasi-static process in thermodynamics, which is W = PΔV, where W is the work done by the gas, P is the constant pressure, and ΔV is the change in volume.
Given:
P = 350 kPa = 350000 Pa (since 1 kPa = 1000 Pa)
ΔV = 0.15 m³ - 0.02 m³ = 0.13 m³
We can now calculate the work done:
W = PΔV
W = 350000 Pa × 0.13 m³
W = 45500 J
Therefore, the piston performs 45500 Joules of work on the gas when the volume increases to 0.15 m³.
Four students use different instruments to measure the length of the same pen. Which measurement implies the greatest precision?
a. 16.0 cm.
b. 0.160 m.
c. 0.00016 km.
d. Need more information.
e. 160.0 mm
Answer:
e. 160.0 mm
Explanation:
Precision is defined as the accuracy in measurement that the measuring instrument measure any given specimen. The instrument having the lowest least count will be more precise than the instrument with higher least count.
Also precision of the reading is given by the number of the significant figures in the given sample of reading.
Option (e) that is 160.0 has a total number of significant figure of 4, which is the largest total significant figures among the other options.
Also the measurement reads 160.0 mm which measure to the lowest possible measurement of the given pen. Thus this reading is more precise.
Hence the correct option is --- Option (e) 160.0 mm
Water flows through a water hose at a rate of Q1 = 620 cm3/s, the diameter of the hose is d1 = 2.27 cm. A nozzle is attached to the water hose. The water leaves the nozzle at a velocity of v2 = 12.8 m/s.
a. Enter an expression for the cross-sectional area of the hose, A1, in terms of its diameter, d1. sig.gif?tid=6C65-32-87-4C-B016-17686
b. Calculate the numerical value of A1, in square centimeters.
c. sig.gif?tid=6C65-32-87-4C-B016-17686Enter an expression for the speed of the water in the hose, v1, in terms of the volume flow rate Q1 and cross-sectional area A1. sig.gif?tid=6C65-32-87-4C-B016-17686
d. Calculate the speed of the water in the hose, v1 in meters per second
e. sig.gif?tid=6C65-32-87-4C-B016-17686Enter an expression for the cross-sectional area of the nozzle, A2, in terms of v1, v2 and A1. sig.gif?tid=6C65-32-87-4C-B016-17686
f. Calculate the cross-sectional area of the nozzle, A2 in square centimeters.
Answer:
a) A₁ = π d₁² / 4 , b) A₁ = 4.05 cm² , c) v₁ = Q / A₁ , d) v₁ = 153 m / s , e) A₂ = A₁ v₁ / v₂, f) A₂= 48.4 cm²
Explanation:
This is a fluid mechanics exercise, let's use the continuity equation
Q = A₁ v₁ = A₂ v₂
Where Q is the flow, A are the areas and v the speeds
a) the area of the hose (A₁) that has a circular section is
A₁ = π r₁²
Since the radius is half the diameter
A₁ = π (d₁ / 2)²
A₁ = π d₁² / 4
b) let's calculate
A₁ = π 2.27²/4
A₁ = 4,047 cm²
A₁ = 4.05 cm²
c) Let's use the left part of the initial equation
Q = A₁ v₁
v₁ = Q / A₁
d) let's calculate the value
v₁ = 620 / 4.05
v₁ = 153 m / s
e) We use the right part of the equation
A₁ v₁ = A₂ v₂
A₂ = A₁ v₁ / v₂
f) Calculate
A₂ = 4.05 153/12.8
A₂= 48.4 cm²
You drop a rock off a bridge. When the rock has fallen 4 m, you drop a second rock. As the two rocks continue to fall, what happens to their velocities?
a. Both increase at the same rate.
b. The velocity of the first rock increases faster than the velocity of the second.
c. The velocity of the second rock increases faster than the velocity of the first.
d. Both velocities stay constant.
Answer:
option A.
Explanation:
The correct answer is option A.
Two rocks are off a bridge first rock is fallen 4 when the second rock is dropped.
Both the rock is dropped under the effect of acceleration due to gravity so, the rate of change of the velocity for both the rock particle will be the same.
Hence, the first rock will reach ground earlier than the second rock because the rate of change of both the rock is at the same rate.
At the time when the two rocks should continue to fall so their velocities should be increased.
The correct answer is option A.
Velocity:When two rocks are off a bridge so here first rock is fallen 4 at the time when the second rock should be fallen. Both the rock should be fallen under the impact of acceleration because of gravity due to which the rate of change of the velocity for both the rock particle should be similar.
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A block rests on a frictionless horizontal surface and is attached to a spring. When set into simple harmonic motion, the block oscillates back and forth with an angular frequency of 7.4 rad/s. The drawing shows the position of the block when the spring is unstrained. This position is labeled ''x = 0 m.'' The drawing also shows a small bottle located 0.080 m to the right of this position. The block is pulled to the right, stretching the spring by 0.050 m, and is then thrown to the left. In order for the block to knock over the bottle,it must be thrown with a speed exceeding v0. Ignoring the width of the block, find v0.
Answer:
v₀ = 0.462 m / s
Explanation:
The spring block system results in an oscillatory movement described by the equation
x = A cos (wt + φ)
Where A is the amplitude of the movement
Let's analyze the situation presented give the angular velocity, the elongation for t = 0 , and they ask me to hit a bottle that is at x = 0.050 m. The speed is given by
v = dx / dt
v = -A w sin (wt + φ)
For the block to hit the bottle the range of motion must be equal to the distance of the bottle
A = 0.080 m
For t = 0
x (0) = A cos φ
Let's calculate the phase
cos φ = x (0) / A
φ= cos⁻¹ (0.5 / 0.8)
φi = 0.8957 rad
Let's use the speed equation
v₀ = -A w sin φ
v₀ = - 0.080 7.4 sin 0.8957
v₀ = 0.462 m / s
The speed of the block, in order for the block to knock over the bottle is 0.462 m/s.
Phase angleThe pahse angle of the wave is determined using the following formula;
x = A cosФ
when the position, x = 0.05 m, and maximum displacement = 0.08 m
0.05 = 0.08cosФ
Ф = cos⁻¹(0.05/0.08)
Ф = 0.896 rad
Speed of blockThe speed of the block, in order for the block to knock over the bottle is calculated as follows;
v = ωA sin(Φ)
v = 7.4 x 0.08 x sin(0.896)
v = 0.462 m/s
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A 200-Ω resistor is connected in series with a 10-µF capacitor and a 60-Hz, 120-V (rms) line voltage. If electrical energy costs 5.0¢ per kWh, how much does it cost to leave this circuit connected for 24 hours?
Answer:
Cost to leave this circuit connected for 24 hours is $ 3.12.
Explanation:
We know that,
[tex]\mathrm{X}_{\mathrm{c}}=\frac{1}{2 \pi \mathrm{fc}}[/tex]
f = frequency (60 Hz)
c= capacitor (10 µF = [tex]10^-6[/tex])
[tex]\mathrm{X}_{\mathrm{c}}=\text { Capacitive reactance }[/tex]
Substitute the given values
[tex]\mathrm{X}_{\mathrm{c}}=\frac{1}{2 \times 3.14 \times 10 \times 10^{-6} \times 60}[/tex]
[tex]\mathrm{X}_{\mathrm{c}}=\frac{1}{3.768 \times 10^{-3}}[/tex]
[tex]\mathrm{x}_{\mathrm{c}}=265.39 \Omega[/tex]
Given that, R = 200 Ω
[tex]X^{2}=R^{2}+X c^{2}[/tex]
[tex]X^{2}=200^{2}+265.39^{2}[/tex]
[tex]X^{2}=40000+70431.85[/tex]
[tex]X^{2}=110431.825[/tex]
[tex]x=\sqrt{110431.825}[/tex]
X = 332.31 Ω
[tex]\text { Current }(I)=\frac{V}{R}[/tex]
[tex]\text { Current }(I)=\frac{120}{332.31}[/tex]
Current (I) = 0.361 amps
“Real power” is only consumed in the resistor,
[tex]\mathrm{I}^{2} \mathrm{R}=0.361^{2} \times 200[/tex]
[tex]\mathrm{I}^{2} \mathrm{R}=0.1303 \times 200[/tex]
[tex]\mathrm{I}^{2} \mathrm{R}=26.06 \mathrm{Watts} \sim 26 \mathrm{watts}[/tex]
In one hour 26 watt hours are used.
Energy used in 54 hours = 26 × 24 = 624 watt hours
E = 0.624 kilowatt hours
Cost = (5)(0.624) = 3.12
Assume that the speed of light in a vacuum has the hypothetical value of 7.58 m/s. In a pickup baseball game, a runner runs at a constant velocity from third base to home plate in a time of 2.50 s, according to the runner. Also according to the runner, the distance covered is 15.0 m. What is the distance covered, according to the catcher who is standing at home plate?
To solve this problem it is necessary to apply the concepts related to relativity.
The distance traveled by the light and analyzed from an observer relative to it is established as
[tex]L = \frac{L_0}{\sqrt{1-\frac{v^2}{c^2}}}[/tex]
Where,
L = Length
c = Speed of light (7.58m/s at this case)
v = Velocity
Our velocity can be reached by kinematic motion equation, where
[tex]v = \frac{d}{t}[/tex]
Here,
d = Distance
t = Time
Replacing
[tex]v = \frac{15}{2.5}[/tex]
[tex]v = 6m/s[/tex]
Replacing at the previous equation,
[tex]L = \frac{L_0}{\sqrt{1-\frac{v^2}{c^2}}}[/tex]
[tex]L = \frac{15}{\sqrt{1-\frac{6^2}{7.58^2}}}[/tex]
[tex]L = 24.5461m[/tex]
Therefore the distance covered, according to the catcher who is standing at home plate is 24.5461m
The moment of inertia of the empty turntable is 1.5 kg?m2. With a constant torque of 2.5 N?m, the turntableperson system takes 3.0 s to spin from rest to an angular speed of 1.0 rad/s. What is the persons moment of inertia about an axis through her center of mass? Ignore friction in the turntable axle.
The moment of inertia of the empty turntable is 1.5 . With a constant torque of 2.5 , the turntableperson system takes 3.0 to spin from rest to an angular speed of 1.0 . What is the persons moment of inertia about an axis through her center of mass? Ignore friction in the turntable axle.
2.5 kg?m2
6.0 kg?m2
7.5 kg?m2
9.0 kg?m2
[tex]6.0 \mathrm{kg} \mathrm{m}^{2}[/tex] is the persons moment of inertia about an axis through her center of mass.
Answer: Option B
Explanation:
Given data are as follows:
moment of inertia of the empty turntable = 1.5
Torque = 2.5 N/m , and
[tex]\text { Angular acceleration of the turntable }=\frac{\text { angular speed }}{\text { time }}=\frac{1}{3}[/tex]
Let the persons moment of inertia about an axis through her center of mass= I
So, Now, from the formula of torque,
[tex]\text { Torque }(\tau)=\text { Moment of inertia(I) } \times \text { Angular acceleration(a) }[/tex]
[tex]2.5=(1.5+I) \times \frac{1}{3}[/tex]
So, from the above equation, we can measure the person’s moment of Inertia (I)
[tex]2.5 \times 3=1.5+I[/tex]
[tex]I=7.5-1.5=6.0 \mathrm{kg} m^{2}[/tex]
A mass of 0.56 kg is attached to a spring and set into oscillation on a horizontal frictionless surface. The simple harmonic motion of the mass is described by x(t) = (0.42 m)cos[(6 rad/s)t]. Determine the following. (a) amplitude of oscillation for the oscillating mass m (b) force constant for the spring N/m (c) position of the mass after it has been oscillating for one half a period m (d) position of the mass one-third of a period after it has been released m (e) time it takes the mass to get to the position x = −0.10 m after it has been released
Answer:
(a) 0.42 m
(b) 20.16 N/m
(c) - 0.42 m
(d) - 0.21 m
(e) 17.3 s
Solution:
As per the question:
Mass, m = 0.56 kg
x(t) = (0.42 m)cos[cos(6 rad/s)t]
Now,
The general eqn is:
[tex]x(t) = Acos\omega t[/tex]
where
A = Amplitude
[tex]\omega[/tex] = angular frequency
t = time
Now, on comparing the given eqn with the general eqn:
(a) The amplitude of oscillation:
A = 0.42 m
(b) Spring constant k is given by:
[tex]\omega = \sqrt{k}{m}[/tex]
[tex]\omega^{2} = \frac{k}{m}[/tex]
Thus
[tex]k = m\omega^{2} = 0.56\times 6^{2} = 20.16\ N/m[/tex]
(c) Position after one half period:
[tex]x(t) = 0.42cos\pi = - 0.42\ m[/tex]
(d) After one third of the period:
[tex]x(t) = 0.42cos(\frac{2\pi}{3}) = - 0.21\ m[/tex]
(e) Time taken to get at x = - 0.10 m:
[tex]-0.10 = 0.42cos6t[/tex]
[tex]6t = co^{- 1} \frac{- 0.10}{0.42}[/tex]
t = 17.3 s
The amplitude of oscillation is 0.42 m. The force constant of the spring is approximately 0.03 N/m. The position of the mass after one half a period, one-third of a period, and at x = -0.10 m can be determined using the given equation x(t).
Explanation:The amplitude of oscillation is the maximum displacement from the equilibrium position. In this case, the amplitude is given as 0.42 m.
The force constant (k) of the spring can be determined using Hooke's Law, which states that the force exerted by a spring is proportional to the displacement from equilibrium. In this case, the force constant is calculated by dividing the mass (0.56 kg) by the square of the angular frequency (6 rad/s) squared, which gives a force constant of approximately 0.03 N/m.
The position of the mass after it has been oscillating for one half a period can be found by substituting the value of time (T/2) into the equation x(t), which gives a position of approximately -0.42 m.
The position of the mass one-third of a period after it has been released can be determined by substituting the value of time (T/3) into the equation x(t), which gives a position of approximately 0.33 m.
The time it takes the mass to get to the position x = -0.10 m after it has been released can be found by rearranging the equation x(t) and solving for time. The time is approximately 0.14 seconds.
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n this example we will look at the periodic motion of an ultrasonic transducer, a kind of ultrasonic loudspeaker used for medical diagnosis. The transducer is oscillating at a frequency of 6.7 MHz (6.7×106Hz). How much time does each oscillation take, and what is the angular frequency?
Answer:
Explanation:
frequency, f = 6.7 MHz = 6.7 x 10^6 Hz
Time period is defined as the time taken by the oscillating body to complete one oscillation.
the formula for the time period is
T = 1/ f = 1 / (6.7 x 10^6) = 1.5 x 10^-7 second
The angular frequency is given by
ω = 2 π f = 2 x 3.14 x 6.7 x 10^6
ω = 4.2 x 10^7 rad/s
The time for each oscillation is approximately 1.49 x 10^-7 seconds, and the angular frequency is approximately 4.21 x 10^7 rad/s.
Explanation:To find the time for each oscillation, we can use the formula T = 1/f, where T represents the period and f represents the frequency. In this case, the frequency is given as 6.7 MHz, which is equivalent to 6.7 x 10^6 Hz. So, substituting the value of the frequency into the formula, we get: T = 1 / (6.7 x 10^6) = 1.49 x 10^-7 seconds. Therefore, each oscillation takes approximately 1.49 x 10^-7 seconds.
The angular frequency can be calculated using the formula ω = 2πf, where ω represents the angular frequency and f represents the frequency. Substituting the given value of the frequency into the formula, we get: ω = 2π x 6.7 x 10^6 = 4.21 x 10^7 rad/s. Therefore, the angular frequency is approximately 4.21 x 10^7 rad/s.