Answer:
Explanation:
Both skaters are initially at rest
Then,
Ux = Uy = 0m/s
It is assumed that it is a frictionless surface
Mass of skater X is less than Y
Mx < My
My > Mx
This shows that,
My = a•Mx,
Such that a > 1
Skater X pushes Y such that it moves with velocity.
Vy = 2Vo to the right, I.e positive x axis
Vy = 2Vo •i
We want to find direction of the velocity of skater X
Using conservation of momentum
Initial momentum =Final momentum
Mx•Ux + My•Uy = Mx•Vx + My• Vy
Ux = Uy = 0,
also My = aMx. And Vy = 2Vo •i
0 + 0 = Mx•Vx + a•Mx•2Vo •i
0 = Mx•Vx + 2a•Mx•Vo •i
Mx•Vx = —2a•Mx•Vo •i
Divide through by Mx
Vx = —2a Vo •i
Therefore, since a is always positive
Then, Vx is in the negative direction or opposite direction to Vy
Now, center of Mass
The center of mass calculated using
Vcm = 1 / M Σ Mi•Vi
Where
M is sum of all the masses
M = Mx + My = Mx + aMx = (a+1) Mx
Then,
Vcm = (Σ Mi•Vi ) / M
Vcm = (MxVx+MyVy) / (a+1)Mx
Vcm=Mx•(-2aVo) +aMx(2Vo)/(a+1)Mx
Vcm = -2a•Mx•Vo + 2a•MxVo / (a+1)Mx
Vcm = 0 / (a+1) Mx
Vcm = 0
So, conclusion
Skater X direction is to the left and the centre of mass is 0.
This options are not written well
Check attachment for correct option
Which of the following careers would require a degree in physics?
A. Art historian
B. War correspondent
C. Nuclear engineer
D. X-ray technician
Answer:
Nuclear engineers require a degree in physics in order to have the job.
Explanation:
An open container holds ice of mass 0.570 kg at a temperature of -17.2 ∘C . The mass of the container can be ignored. Heat is supplied to the container at the constant rate of 820 J/minute . The specific heat of ice to is 2100 J/kg⋅K and the heat of fusion for ice is 334×103J/kg.
The time required to raise the temperature of the ice from -17.2 °C to 0 °C is approximately 6.22 minutes.
Explanation:To calculate the time required for the temperature of the ice to rise from -17.2 °C to 0 °C, we can use the equation Q=mcΔT, where Q is the heat supplied, m is the mass of the ice, c is the specific heat of ice, and ΔT is the change in temperature.
The heat supplied (Q) during this process is used to raise the temperature of the ice without causing a phase change. Given that Q=820J/min and c=2100J/kg⋅K, we rearrange the equation to solve for time (t): t=Q/mcΔT
Substituting the given values (m=0.570kg, ΔT=0°C−(−17.2°C)=17.2°C), we find t≈820J/min/ (0.570kg)(2100J/kg⋅K)(17.2°C) ≈6.22min.
This calculation assumes that all the heat supplied is used to raise the temperature of the ice without considering the heat required for a phase change. To account for the heat of fusion during the phase change from ice to water at 0 °C, an additional calculation would be needed. However, the question specifies raising the temperature to 0 °C, so the heat of fusion is not considered in this particular scenario.
Understanding the principles of heat transfer, specific heat, and phase changes is essential in solving thermodynamics problems. These principles are widely applicable in various scientific and engineering fields, providing insights into the behavior of materials under different conditions.
The shaft is supported by a smooth thrust bearing at B and a journal bearing at C. Determine the resultant internal loadings acting on the cross section at E. Suppose that P1 = 360 lb , P2 = 830 lb . Part a, b, and c please.
Final answer:
To determine the resultant internal loadings at the cross section at E, we calculate the reaction forces at points B and C. The reaction force at B is 360 lb directed towards the left due to the thrust bearing, while the reaction force at C is 830 lb directed towards the right due to the journal bearing. Combining these forces, the resultant force at E is 1190 lb directed towards the right.
Explanation:
To determine the resultant internal loadings acting on the cross-section at E, we need to consider the forces acting on the shaft at points B and C. Part a requires determining the reaction force at B due to the thrust bearing, part b requires determining the reaction force at C due to the journal bearing, and part c requires combining the forces to find the resultant internal loadings at E.
For part a, since the shaft is supported by a smooth thrust bearing at B, the reaction force at B will be equal in magnitude and opposite in direction to the applied force P1. Therefore, the reaction force at B is 360 lb directed towards the left.
For part b, since the shaft is supported by a journal bearing at C, the reaction force at C will be equal in magnitude to the applied force P2. Therefore, the reaction force at C is 830 lb directed towards the right.
For part c, to find the resultant force at E, we need to combine the forces at B and C. Since the forces are along the same line of action, we can simply add the magnitudes of the forces. The resultant force at E is equal to the sum of the reaction forces at B and C, which is (360 lb) + (830 lb) = 1190 lb directed towards the right.
To understand the formula representing a traveling electromagnetic wave.
Light, radiant heat (infrared radiation), X rays, and radio waves are all examples of traveling electromagnetic waves. Electromagnetic waves comprise combinations of electric and magnetic fields that are mutually compatible in the sense that the changes in one generate the other.
The simplest form of a traveling electromagnetic wave is a plane wave. For a wave traveling in the x direction whose electric field is in the y direction, the electric and magnetic fields are given by
E? =E0sin(kx??t)j^,
B? =B0sin(kx??t)k^.
This wave is linearly polarized in the y direction.
1.a. In these formulas, it is useful to understand which variables are parameters that specify the nature of the wave. The variables E0 and B0are the __________ of the electric and magnetic fields.
Choose the best answer to fill in the blank.
1. maxima
2. amplitudes
3. wavelengths
4. velocities
b. The variable ? is called the __________ of the wave.
Choose the best answer to fill in the blank.
1. velocity
2. angular frequency
3. wavelength
c. The variable k is called the __________ of the wave.
Choose the best answer to fill in the blank.
1. wavenumber
2. wavelength
3. velocity
4. frequency
d. What is the mathematical expression for the electric field at the point x=0,y=0,z at time t?
1. E=E0sin(??t)j^
2. E =E0sin(??t)k^
3. E =0
4. E =E0sin(kz??t)i^
5. E =E0sin(kz??t)j^
e. For a given wave, what are the physical variables to which the wave responds?
1. x only
2. t only
3. k only
4. ? only
5. x and t
6. x and k
7. ? and t
8. k and ?
Answer:
please read the answer below
Explanation:
We have that both electric field and magnetic field are given by:
[tex]\vec{E}=E_osin(kx-\omega t)\hat{j}\\\\\vec{B}=B_osin(kx-\omega t)\hat{k}[/tex]
I complete with bold words the answers:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
a. In these formulas, it is useful to understand which variables are parameters that specify the nature of the wave. The variables E0 and B0are the magnitudes of the electric and magnetic fields.
2. amplitudes
b. The variable w is called the angular frequency of the wave.
2. angular frequency
c. The variable k is called the wavenumber of the wave.
1. wavenumber
c.
1. E =E0sin(wt)k^
d.
6. x and t
hope this helps!!
A light beam is directed parallel to the axis of a hollow cylindrical tube. When the tube contains only air, the light takes 8.72 ns to travel the length of the tube, but when the tube is filled with a transparent jelly, the light takes 1.82 ns longer to travel its length. What is the refractive index of this jelly?
Answer:
Explanation:
velocity of light in a medium of refractive index V = V₀ / μ
V₀ is velocity of light in air and μ is refractive index of light.
time to travel in tube with air = length of tube / velocity of light
8.72 ns = L / V₀ L is length of tube .
time to travel in tube with jelly = length of tube / velocity of light
8.72+ 1.82 = L / V L is length of tube .
10.54 ns = L / V
dividing the equations
10.54 / 8.72 = V₀ / V
10.54 / 8.72 = μ
1.21 = μ
refractive index of jelly = 1.21 .
Understand Key Concepts
Which is NOT a fluid?
A. helium
B. ice
C. milk
D.Water
Answer:
The answer is A, friend.
A bat can detect small objects such as an insect whose size is approximately equal to the wavelength of the sound the bat makes. What is the smallest insect a bat can detect? Assume that bats emit a chirp at a frequency of 47.6 kHz, and that the speed of sound in air is 413 m/s. Answer in units of mm.
Given that,
Frequency emitted by the bat, f = 47.6 kHz
The speed off sound in air, v = 413 m/s
We need to find the wavelength detected by the bat. The speed of a wave is given by formula as follows :
[tex]v=f\lambda\\\\\lambda=\dfrac{v}{f}\\\\\lambda=\dfrac{413}{47.6\times 10^3}\\\\\lambda=0.00867\ m[/tex]
or
[tex]\lambda=8.67\ mm[/tex]
So, the bat can detect small objects such as an insect whose size is approximately equal to the wavelength of the sound the bat makes i.e. 8.67 mm.
An airplane is initially flying horizontally (not gaining or losing altitude), and heading exactly North. Suppose that the earth's magnetic field at this point is also exactly horizontal, and points from South to North (it really does!). The airplane now starts a different motion. It maintains the same speed, but gains altitude at a constant rate, still heading North. The magnitude of the electric potential difference between the wingtips has... [Remember that the airplane is made of metal, and is a conductor] Group of answer choices
Note: The answer choices are :
a) Increased
b) Decreased
c) stayed the same
Answer:
The correct option is Increased
The magnitude of the electric field potential difference between the wingtips increases.
Explanation:
The magnitude of the electric potential difference is the induced emf and is given by the equation:
[tex]emf = l (v \times B)[/tex]
where l = length
v = velocity
B = magnetic field
As the altitude of the airplane increases, the magnetic flux becomes stronger, the speed of the airplane becomes perpendicular to the magnetic field, i.e. [tex]v \times B = vB sin90 = vB\\[/tex] ,
the induced emf = vlB, and thus increases.
The magnitude of the electric field potential difference between the wingtips increases
A capacitor consists of a set of two parallel plates of area A separated by a distance d . This capacitor is connected to a battery that maintains a constant potential difference V across the plates. If the separation between the plates is doubled, the electrical energy stored in the capacitor will be
Answer:
if we double the distance the energy stored will be doubled also
Explanation:
The energy stored in a capacitor is given as
Energy stored =1/2(cv²)
Or
= 1/2(Qv)
Where c = capacitance
Q= charge
But the electric field is expressed as
E= v/d
where v= voltage
d= distance
v=Ed
Substituting into any equation above say
Energy stored =1/2(Qv)
Substituting v=Ev
Energy stored =1/2(QEd)
From the equation above it shows that if we double the distance The energy stored will be doubled also
Review the multiple-concept example as an aid in solving this problem. In a fast-pitch softball game the pitcher is impressive to watch, as she delivers a pitch by rapidly whirling her arm around so that the ball in her hand moves on a circle. In one instance, the radius of the circle is 0.685 m. At one point on this circle, the ball has an angular acceleration of 63.8 rad/s2 and an angular speed of 15.0 rad/s. (a) Find the magnitude of the total acceleration (centripetal plus tangential) of the ball.
Answer:
Total acceleration will be [tex]160.20rad/sec^2[/tex]
Explanation:
We have given radius of the circle r = 0.685 m
Angular acceleration [tex]\alpha =63.8rad/sec^2[/tex]
Angular speed [tex]\omega =15rad/sec[/tex]
Centripetal acceleration will be
[tex]a_c=\omega ^2r=15^2\times 0.685=154.125rad/sec^2[/tex]
Tangential acceleration will be
[tex]a_t=r\alpha =0.685\times 63.8=43.7rad/sec^2[/tex]
(a) Total acceleration will be equal to
[tex]a=\sqrt{a_t^2+a_c^2}[/tex]
[tex]a=\sqrt{43.7^2+154.125^2}=160.20rad/sec^2[/tex]
So total acceleration will be [tex]160.20rad/sec^2[/tex]
Two very small planets orbit a much larger star. Planet A orbits the star with a period TA . Planet B orbits the star at four times the distance of planet A, but planet B is four times as massive as planet A. Assume that the orbits of both planets are approximately circular.
Planet B orbits the star with a period TB equal to
a. TA/4.
b. 16TA.
c. 8TA.
d. 4TA
d. TA
Answer:
Explanation:
Given that,
Period of Planet A around the star
Pa = Ta
Let the semi major axis of planet A from the star be
a(a) = x
Given that, the distance of Planet B from the star (i.e. it semi major axis) is 4 time that of Planet A
a(b) = 4 × a(a) = 4 × x
a(b) = 4x
Also planet B is 4 times massive as planet A
Using Kepler's law
P² ∝a³
P²/a³ = k
Where
P is the period
a is the semi major axis
Then,
Pa² / a(a)³ = Pb² / a(b)³
Pa denotes Period of Planet A and it is Pa = Ta
a(a) denoted semi major axis of planet A and it is a(a) = x
Pb is period of planet B, which is the required question
a(b) is the semimajor axis of planet B and it is a(b) = 4x
So,
Ta² / x³ = Pb² / (4x)³
Ta² / x³ = Pb² / 64x³
Cross multiply
Ta² × 64x³ = Pb² × x³
Divide both sides by x³
Ta² × 64 = Pb²
Then, Pb = √(Ta² × 64)
Pb = 8Ta
Then, the period of Planet B is eight times the period of Planet A.
The correct answer is C
The period of orbit for planet B is 4 times the period of orbit for planet A.
Explanation:To determine the period of orbit for planet B, we can use Kepler's Third Law, which states that the square of the period of an orbit is proportional to the cube of its average distance from the center of attraction. Since planet B is four times the distance of planet A and four times as massive, its period will be 4^3/4^2 times that of planet A. Simplifying, this means that TB = 4 * TA, so the correct answer is d. 4TA.
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2. An electrical heater 200mm long and 15mm in diameter is inserted into a drilled hole normal to the surface of a large block of material having a thermal conductivity of 5W/m·K. Estimate the temperature reached by the heater when dissipating 25 W with the surface of the block at a temperature of 35 °C.
Answer:
The final temperature is 50.8degrees celcius
Explanation:
Pls refer to attached handwritten document
Answer: 50.63° C
Explanation:
Given
Length of heater, L = 200 mm = 0.2 m
Diameter of heater, D = 15 mm = 0.015 m
Thermal conductivity, k = 5 W/m.K
Power of the heater, q = 25 W
Temperature of the block, = 35° C
T1 = T2 + (q/kS)
S can be gotten from the relationship
S = 2πL/In(4L/D)
On substituting we have
S = (2 * 3.142 * 0.2) / In (4 * 0.2 / 0.015)
S = 1.2568 / In 53.33
S = 1.2568 / 3.98
S = 0.32 m
Proceeding to substitute into the main equation, we have
T1 = T2 + (q/kS)
T1 = 35 + (25 / 5 * 0.32)
T1 = 35 + (25 / 1.6)
T1 = 35 + 15.625
T1 = 50.63° C
Suppose that the mirror described in Part A is initially at rest a distance R away from the sun. What is the critical value of area density for the mirror at which the radiation pressure exactly cancels out the gravitational attraction from the sun?
The critical area density for a mirror in space where radiation pressure cancels out gravitational attraction can be computed using the principles of radiation pressure and gravitational force. By equating the momentum transfer from reflected sunlight to the gravitational pull of the Sun, one can find the area density at which these forces balance.
The question posed is about finding the critical area density for a mirror located in space at a distance R from the Sun, where the radiation pressure from sunlight would balance the gravitational attraction exerted by the Sun. The solution to this problem involves using the principle of momentum transfer from sunlight and equating it to the gravitational force to derive the density at which the forces are balanced.
The radiation pressure P exerted by sunlight can be calculated using the formula P = 2I/c, where I is the intensity of sunlight and c is the speed of light. Given that sunlight above Earth's atmosphere has an intensity of 1.30 kW/m², the radiation pressure P would be twice this value divided by the speed of light, due to the reflection phenomenon (momentum is doubled as the direction is reversed).
On the other hand, the gravitational force acting on an object is given by the formula F = GMm/R², where G is the gravitational constant, M is the mass of the Sun, m is the mass of the object (or spacecraft with the mirror), and R is the distance from the Sun. The mass m can be represented in terms of the area density ρA, where ρ is the area density and A is the area of the mirror.
Setting the radiation pressure equal to the gravitational force and solving for ρ will yield the critical value of area density at which the two forces cancel out.
The critical value of area density for the mirror at which the radiation pressure exactly cancels out the gravitational attraction from the sun is:
[tex]\[ \sigma = \frac{P_{sun}}{4\pi G M_{sun} R^2 c} \][/tex]
To find the critical value of area density (σ) for the mirror at which the radiation pressure exactly cancels out the gravitational attraction from the sun, we need to set the radiation pressure equal to the gravitational force per unit area.
Let's denote the radiation pressure as [tex]\( P_{rad} \)[/tex] and the gravitational force per unit area as [tex]\( P_{grav} \)[/tex]
The radiation pressure [tex]\( P_{rad} \)[/tex] can be calculated using the formula:
[tex]\[ P_{rad} = \frac{I}{c} \][/tex]
where [tex]\( I \)[/tex] is the intensity of the sunlight at the mirror's position and [tex]\( c \)[/tex] is the speed of light.
The intensity [tex]\( I \)[/tex] at a distance [tex]\( R \)[/tex] from the sun can be found using the inverse square law:
[tex]\[ I = \frac{P_{sun}}{4\pi R^2} \][/tex]
where [tex]\( P_{sun} \)[/tex] is the total power output of the sun.
The gravitational force per unit area [tex]\( P_{grav} \)[/tex] is given by:
[tex]\[ P_{grav} = \frac{F_{grav}}{A} = \frac{G M_{sun} m_{mirror} / R^2}{A} \][/tex]
where [tex]\( G \)[/tex] is the gravitational constant, [tex]\( M_{sun} \)[/tex] is the mass of the sun, [tex]\( m_{mirror} \)[/tex] is the mass of the mirror, and [tex]\( A \)[/tex] is the area of the mirror.
Since [tex]\( m_{mirror} = \sigma A \), where \( \sigma \)[/tex] is the area density of the mirror, we can write:
[tex]\[ P_{grav} = \frac{G M_{sun} \sigma A / R^2}{A} = \frac{G M_{sun} \sigma}{R^2} \][/tex]
Now, we set [tex]\( P_{rad} = P_{grav} \)[/tex] to find the critical value of [tex]\( \sigma \)[/tex]:
[tex]\[ \frac{I}{c} = \frac{G M_{sun} \sigma}{R^2} \][/tex]
Substituting [tex]\( I \)[/tex] from the intensity equation, we get:
[tex]\[ \frac{P_{sun}}{4\pi R^2 c} = \frac{G M_{sun} \sigma}{R^2} \][/tex]
Solving for [tex]\( \sigma \)[/tex], we find:
[tex]\[ \sigma = \frac{P_{sun}}{4\pi R^2 c} \cdot \frac{1}{G M_{sun}} \][/tex]
[tex]\[ \sigma = \frac{P_{sun}}{4\pi G M_{sun} R^2 c} \][/tex]
Complete question:- Suppose that the mirror described in Part
A firm wants to determine the amount of frictional torque in their current line of grindstones, so they can redesign them to be more energy efficient. To do this, they ask you to test the best-selling model, which is basically a diskshaped grindstone of mass 1.1 kg and radius 0.09 m which operates at 73.3 rad/s. When the power is shut off, you time the grindstone and find it takes 42.4 s for it to stop rotating. What is the frictional torque exerted on the grindstone in newton-meters
Explanation:
Mass of the diskshaped grindstone, m = 1.1 kg
Radius of disk, r = 0.09 m
Angular velocity, [tex]\omega=73.3\ rad/s[/tex]
Time, t = 42.4 s
We need to find the frictional torque exerted on the grindstone. Torque in the rotational kinematics is given by :
[tex]\tau=I\alpha[/tex]
I is moment of inertia of disk, [tex]I=\dfrac{mr^2}{2}[/tex]
[tex]\tau=\dfrac{mr^2\alpha }{2}\\\\\tau=\dfrac{1.1\times (0.09)^2\times 73.3 }{2\times 42.4}\\\\\tau=7.7\times 10^{-3}\ N-m[/tex]
So, the frictional torque exerted on the grindstone is [tex]7.7\times 10^{-3}\ N-m[/tex].
a 150 kg person stands on a compression spring with spring constant 10000 n/m and nominal length of 0.50 what is the total length
Answer:
The total length is 0.65m.
Explanation:
The total length [tex]x_{tot}[/tex] of the spring is equal to its length [tex]x_0[/tex] right now (0.50 m ) plus the amount [tex]x[/tex] by which it is compressed due to weight of the man:
[tex]x_{tot} = x_0+x[/tex]
The spring compression is given by Hooke's law:
[tex]F = -kx[/tex]
which in our case gives
[tex]-Mg = -kx[/tex]
solving for [tex]x[/tex] we get:
[tex]x= \dfrac{Mg}{k }[/tex]
putting in [tex]M = 150kg, g= 10m/s^2[/tex] and [tex]k = 10,000N/m[/tex] we get:
[tex]x= \dfrac{(150kg)(10m/s^2)}{10,000N/m^2}[/tex]
[tex]x = 0.15m[/tex]
Hence, the total length of the spring is
[tex]x_{tot} = 0.50m+0.15m[/tex]
[tex]\boxed{x_{tot} = 0.65m.}[/tex]
A nearsighted person cannot see objects further away than 10 m clearly. This person wants to be able to see objects 300 m away without trouble. What is the focal length of the lens you would prescribe? (Ignore the distance between the person’s eye and the lens.)
a. 9.7 m
b. – 9.7 m
c. No such lens can be prescribed.
d. 10.3 m
e. – 30 m
f. 30 m
g. – 10.3 m
Answer:
d.-10.3m
Explanation:
Note for short sightedness the focal length is negative
Let do be object distance=10m
And di= image distance=-300m
Using lens formula
F=do*di/do-di= 10*300/10-300=-10.3m
Answer:
d. 10.3 m
Explanation:
For a nearsighted person,
1/f = (1/v)+(1/u).................... Equation 1
f = focal, v = image distance, u = object distance.
f = vu/(v+u)................. Equation 2
Given: v = -10 m, u = 300 m
Substitute into equation 2
f = (-10×300)/(-10+300)
f = -3000/290
f = -10.34 m
therefore a concave lens of focal length 10.34 m is required.
The right option is d. 10.3 m
A laser shines on a pair of vertical slits. The horizontal distance L 1 between the laser and the ruler is 12.3 m. The distance L 2 between the laser and the slits is 0.511 m. The distance d is 0.440 mm. A laser is located a distance L subscript 1 from a ruler and a distance L subscript 2 from a barrier containing two, narrow slits. The slit separation is d. An interference intensity pattern is shown at the position of the ruler. The intensity pattern has a central maximum at 0 centimeters. The first dark fringe is at plus or minus 1.6 centimeters. The first bright fringe is at about plus or minus 3 centimeters. The second dark fringe is at about plus or minus 4.8 centimeters. The second bright fringe is at about plus or minus 6.4 centimeters. The third dark fringe is at plus or minus 8 centimeters. The illustration is not to scale. Note that the ruler measures in centimeters. Calculate the wavelength ? of the light.
To calculate the wavelength of the light, use the equation d sin θ = mλ. Plugging in the values, we find that the wavelength is 563 nm.
Explanation:In order to calculate the wavelength of the light, we can use the equation d sin θ = mλ, where d is the slit separation, θ is the angle of the bright fringe, m is the order of the fringe, and λ is the wavelength of the light. In this case, we are given the slit separation (0.0100 mm) and the angle of the third bright line (10.95°). We can rearrange the equation to solve for λ:
λ = d sin θ / m
Plugging in the values, we get:
λ = (0.0100 mm) sin(10.95°) / 3
λ = 5.63 x 10-7 mm or 563 nm
An inversion in a permutation of the integers 1 to n is a pair of numbers (not necessarily adjacent) such that the larger number is listed first. For example, in the permutation 4, 2, 3, 1, the inverted pairs are (4, 2), (4, 3), (4, 1) (2, 1) and (3, 1). By listing out all 24 permutations and counting the number of inversions in each (if you are lazy you can write a program to do this and attach the code as a separate file), calculate the expected number of inversions in a random permutation of 1, 2, 3 and 4. Then, using this result, posit a guess for the general result, in terms of n for permutations of 1, 2, 3, …, n. Try to prove this guess via a route that uses less calculation, but looks at an arbitrary pair of indexes into the permutation, say i and j with i < j and counts how many permutations for which this pair is "in order" and that this pair is in inverted.
Answer:
The total permutation = nP2
The inversions = nC2
Explanation:
Please look at the solution in the attached Word file
A physicist's right eye is presbyopic (i.e., farsighted). This eye can see clearly only beyond a distance of 97 cm, which makes it difficult for the physicist to read books and journals. Find the focal length and power of a lens that will correct this presbyopia for a reading distance of 25 cm, when worn 2 cm in front of the eye
The issue of farsightedness or presbyopia can be corrected by a converging lens with a focal length of 34 cm and power of 2.94 Diopters.
Explanation:The provided problem can be solved using the lens formula which is 1/f = 1/v - 1/u, where f = focal length, v = image distance, and u = object distance. The image distance (di) for clear vision should match the lens-to-retina distance, which is constant and taken as 2 cm for the given question. The lens that the physicist is recommended to use should create an image with a reading distance of 25 cm and therefore this will be ‘v’. However, the lens is worn 2 cm in front of the eye and hence the actual image distance becomes 27 cm (or 0.27 m). The object is however at a distance of 97 cm (0.97 m) as indicated by the problem. When we plug these values into the lens formula, we get f = 1 / {(1/0.27) - (1/0.97)} which is approximately equal to 0.34 m or 34 cm. The optical power of lens (P) is reciprocal of the focal length in meters. Hence P = 1/f = 1/0.34 = 2.94 D.
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To correct the physicist's presbyopia for clear vision at 25 cm, a lens with a focal length of approximately -30.35 cm (or -0.3035 m) and a power of around -3.29 diopters is needed. The lens formula helped in determining these values.
Correcting Farsightedness
A presbyopic eye has difficulty seeing objects clearly at close range. In this case, the physicist's eye can only see clearly beyond 97 cm. To correct this and allow clear vision at 25 cm, we need to determine the focal length and power of the corrective lens when worn 2 cm in front of the eye.
Using the lens formula:
1/f = 1/v - 1/u
where:
f is the focal length of the lensv is the image distance (97 cm minus 2 cm = 95 cm)u is the object distance (25 cm minus 2 cm = 23 cm)Substituting the values, we get:
1/f = 1/95 - 1/23
1/f = (23 - 95) / (95 * 23)
1/f = -72 / 2185
f = -2185 / 72 ≈ -30.35 cm
Therefore, the focal length of the lens is approximately -30.35 cm (or -0.3035 m).
The power of the lens (P) is given by the formula:
P = 1/f (in meters)
Substituting the focal length:
P = 1 / -0.3035 ≈ -3.29 diopters (D)
Hence, the power of the corrective lens needed is approximately -3.29 D.
A current of 6 A runs through a coffee machine connected to a 120 V circuit. What is the resistance of the coffee machine?
Answer:
20 ohm
Explanation:
V = I x R
R = V/ I
= 120/6
R = 20 ohm
Considering the Ohm's law, the resistance of the coffee machine is 20 Ω.
Definition of currentThe current (I) is a measure of the speed at which the charge passes a given reference point in a specified direction. Its unit of measure is amps (A).
Definition of voltageThe driving force (electrical pressure) behind the flow of a current is known as voltage and is measured in volts (V). That is, voltage is a measure of the work required to move a charge from one point to another.
Definition of resistanceResistance (R) is the difficulty that a circuit opposes to the flow of a current and it is measured in ohms (Ω).
Ohm's lawOhm's law establishes the relationship between current, voltage, and resistance in an electrical circuit.
This law establishes that the intensity of the current that passes through a circuit is directly proportional to the voltage of the same and inversely proportional to the resistance that it presents:
I= V÷R
Where:
I is the current measured in amps (A).V the voltage measured in volts (V).R the resistance that is measured in ohms (Ω).Resistance of the coffee machineIn this case, you know that:
The voltage is 120 V.The current through the coffee machine is 6 A.Replacing in the Ohm's Law:
6 A= 120 V÷R
Solving:
6 A× R= 120 V
R= 120 V÷6 A
R= 20 Ω
Finally, the resistance of the coffee machine is 20 Ω.
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What is the best way to determine levelness?
A.See if the Acceleration versus Time for both directions are both zero.
B.Plot the Acceleration versus Time for one direction and acceleration should be zero.
C.Plot Position versus Time and compare the linear fit from each direction of travel; slopes should be equal.
D.Plot Position versus Time and compare the linear fit from each direction of travel; slopes should be equal but opposite.
E.Plot Velocity versus Time for both directions; slopes should be equal.
F.See if slope of Velocity versus Time for both directions are equal but opposite.
Answer:
F. See if the slope of Velocity versus Time for both directions are equal but opposite.
Explanation: Velocity is the rate of change of position. The slope of a distance or position-time graph is velocity. Acceleration is the rate of change of velocity. The slope of a velocity-time graph is acceleration.
A velocity-time graph shows changes in the velocity of a moving object over time. The slope of a velocity-time graph represents an acceleration of the moving object.
So, the value of the slope at a particular time represents the acceleration of the object at that instant.
21. (a) Aircraft sometimes acquire small static charges. Suppose a supersonic jet has a 0.500-μC charge and flies due west at a speed of 660. m/s over Earth’s south magnetic pole, where the 8.00 × 10−5 − T magnetic field points straight down into the ground. What are the direction and the magnitude of the magnetic force on the plane? (b) Discuss whether the value obtained in part (a) implies this is a significant or negligible effect.
Answer:
Explanation:
The picture attached shows the full explanation and i hope it helps. Thank you
Final answer:
The magnetic force on a supersonic jet with a 0.500-μC static charge, flying over the Earth's south magnetic pole at 660 m/s, is 7.50 × 10-7 N, directed to the north. This effect is considered negligible given the small magnitude of the force.
Explanation:
When an aircraft with a static charge flies through the Earth's magnetic field, it experiences a magnetic force due to the interaction between its charge, its velocity, and the magnetic field. This is a concept from electromagnetism, specifically the Lorentz force. The magnitude of the magnetic force (F) can be calculated using the equation F = qvBsin(θ), where q is the charge on the aircraft, v is the speed of the aircraft, B is the magnetic field strength, and θ is the angle between the velocity of the charge and the direction of the magnetic field.
For a supersonic jet with a 0.500-μC (or 0.500x10-6 C) charge flying due west over the Earth's south magnetic pole, where the magnetic field (B) is 8.00 × 10-5 T and points straight down (θ = 90 degrees), the magnitude of the magnetic force is:
F = (0.500x10-6 C)(660 m/s)(8.00 × 10-5 T)sin(90 degrees) = 7.50 × 10-7 N, perpendicular to both the magnetic field lines and the velocity of the jet (which means it points either north or south). Since the jet is flying due west and the magnetic field is down, the right-hand rule indicates the force will push the jet to the north.
Regarding part (b), since the magnetic force magnitude, 7.50 × 10-7 N, is quite small compared to the typical forces experienced by a supersonic jet, such as thrust, drag, and lift, it can be considered a negligible effect. It's unlikely to have any significant impact on the flight of the aircraft.
How do the electrons in the bulb's filament, far from the battery and its emf, "know" that they should flow?
Answer:this is obviously because free electrons can easily move in the metal due to potential difference, and they are inserted in the wire from the negative terminal of the battery and pulled away ( come back) from the wire into the battery at positive terminal.
Electrons in a lightbulb filament flow due to the electric fields created by a connected battery, encountering resistance that dissipates energy as heat and allows the bulb to emit light.
Explanation:Electrons 'know' to flow in a bulb's filament due to the electric fields created when a battery is connected to a circuit. These fields exert a force on the electrons, causing them to move. The flow of electrons is sustained by the potential difference (emf) provided by the battery, but it's not perpetual because as electrons move through the resistive filament, they encounter resistance analogous to friction, which causes energy to be dissipated as heat. This is the principle by which the bulb emits light. An open circuit, like if a wire is cut, prevents the flow of charge, demonstrating the necessity of a closed path for current to flow.
The resistance to electron movement through the filament is due to interactions with the material's atoms, as described by Newton's second law (a = Ftotal/m). This resistance leads to the conversion of electrical energy into heat, which in the case of an incandescent lightbulb, is necessary for it to glow. Without resistance, electrons accelerated by the emf would continue gaining kinetic energy, which does not occur due to this energy transformation. The steady flow of electrons is the result of these resisting forces balancing out the force exerted by the electric field, leading to a constant flow of current as long as the circuit is complete.
To introduce you to the concept of escape velocity for a rocket. The escape velocity is defined to be the minimum speed with which an object of mass mmm must move to escape from the gravitational attraction of a much larger body, such as a planet of total mass MMM. The escape velocity is a function of the distance of the object from the center of the planet RRR, but unless otherwise specified this distance is taken to be the radius of the planet because it addresses the question "How fast does my rocket have to go to escape from the surface of the planet?"
Answer:
11.206 km/s
Explanation: to leave the surface of the earth, you velocity Ve must be;
Escape velocity Ve = (2gRe)^0.5
Where g = acceleration due to gravity 9.81 m/s^2
Re = earth's radius 6400 km = 6.4x10^6
Ve = (2 x 9.81 x 6.4 x 10^6)^0.5
Ve = (125568000)^0.5
Ve = 11205.7 m/s
= 11.206 km/s
Suppose that the inverse market demand for silicone replacement tips for Sony earbud headphones is p = pN - 0.1Q, where p is the price per pair of replacement tips, pN is the price of a new pair of headphones, and Q is the number of tips per week. Suppose that the inverse supply function of the replacement tips is p = 2 + 0.012 Q. a. The effect of a change in the price of a new pair of headphones on the equilibrium price of replacement tips ( dp/dpN) at the equilibrium is given by nothing (Round your answer to three places.)
The effect of a change in the price of new Sony headphones on the equilibrium price of silicone replacement tips can't be accurately calculated from the provided equations without numerical values. An increase in the price of new headphones would likely lead to a surge in demand for replacement parts, thereby increasing their equilibrium price.
Explanation:The student is asking about the impact of a change in the price of the new Sony headphones on the equilibrium price of replacement tips. The inverse demand function is given by p = pN - 0.1Q, and the inverse supply function is given by p = 2 + 0.012Q. The equilibrium condition is that the quantity demanded equals the quantity supplied, so we set the demand equation equal to the supply equation and solve for Q and p. Now to find the effect of a change in the price of the new headphones on the equilibrium price of the replacement tips, we need to differentiate the equilibrium price with respect to the price of the new headphones. This essentially involves implicit differentiation of the equilibrium condition.
However, due to the nature of the equations, getting a definitive value for dp/dpN would be difficult without numerical values to plug in. As such, the phrase 'dp/dpN is given by nothing' may have been a typographical error or misunderstanding. An increase in the price of new headphones would likely increase demand for replacement parts, thus raising their equilibrium price. But we cannot compute dp/dpN definitively from the provided equations.
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A fisherman notices that his boat is moving up and down periodically without any horizontal motion, owing to waves on the surface of the water. It takes a time of 2.60 s for the boat to travel from its highest point to its lowest, a total distance of 0.630 m. The fisherman sees that the wave crests are spaced a horizontal distance of 5.50 m apart.
How much is the wavelength?
The question is incomplete! Complete question along with answer and step by step explanation is provided below.
Question:
A fisherman notices that his boat is moving up and down periodically without any horizontal motion, owing to waves on the surface of the water. It takes a time of 2.60 s for the boat to travel from its highest point to its lowest, a total distance of 0.630 m. The fisherman sees that the wave crests are spaced a horizontal distance of 5.50 m apart.
How much is the wavelength?
How fast are the waves traveling ?
What is the amplitude A of wave?
Given Information:
time = t = 2.60 s
wavelength = λ = 5.50 m
distance = d = 0.630 m
Required Information:
a) wavelength = λ = ?
b) speed = v = ?
c) Amplitude = A = ?
Answer:
a) wavelength = 5.50 m
b) speed = 1.056 m/s
c) Amplitude = 0.315 m
Step-by-step explanation:
a)
It is given that wave crests are spaced a horizontal distance of 5.50 m apart that is basically the wavelength so,
λ = 5.50 m
b)
We know that the speed of the wave is given by
v = λf
where λ is the wavelength and f is the frequency of the wave given by
f = 1/T
Where T is the period of the wave.
Since the it is given that boat takes 2.60 s to travel from its highest point to its lowest that is basically half of the period so one full period is
T = 2*2.60
T = 5.2 s
So the frequency is,
f = 1/5.2
f = 0.192 Hz
Therefore, the speed is
v = λf
v = 5.50*0.192
v = 1.056 m/s
c)
The amplitude of the wave is given by
A = d/2
where d is the distance from the highest point to the lowest, therefore, the amplitude is half of it.
A = 0.630/2
A = 0.315 m
There are two categories of ultraviolet light. Ultraviolet A ( UVA ) has a wavelength ranging from 320 nm to 400 nm . It is not so harmful to the skin and is necessary for the production of vitamin D. UVB, with a wavelength between 280 nm and 320 nm , is much more dangerous, because it causes skin cancer.
Find the frequency ranges of UVA.
Enter your answers separated with commas.
Answer:
[tex]7.5x10^{14}Hz[/tex], [tex]9.37x10^{14}Hz[/tex].
Explanation:
The ultraviolet light belongs to the electromagnetic spectrum.
The electromagnetic spectrum is the distribution of radiation due to the different frequencies at which it radiates and its different intensities. That radiation is formed by electromagnetic waves, which are transverse waves formed by an electric field and a magnetic field perpendicular to it.
Any radiation from the electromagnetic spectrum has a speed of [tex]3x10^{8}m/s[/tex] in vacuum.
Therefore, in order to know the frequency the following equation can be used:
[tex]c = \nu \cdot \lambda[/tex] (1)
[tex]\nu = \frac{c}{\lambda}[/tex] (2)
Where [tex]\nu[/tex] is frequency, c is the speed of light and [tex]\lambda[/tex] is the wavelength.
Notice that it is necessary to express the wavelength in units of meters before it can be used in equation 2.
[tex]\lambda = 320nm . \frac{1m}{1x10^{9}nm}[/tex] ⇒ [tex]3.2x10^{-7}m[/tex]
[tex]\nu = \frac{3x10^{8}m/s}{3.2x10^{-7}m}[/tex]
[tex]\nu = 9.37x10^{14}s^{-1}[/tex]
But [tex]1Hz = s^{-1}[/tex]
[tex]\nu = 9.37x10^{14}Hz[/tex]
[tex]\lambda = 400nm . \frac{1m}{1x10^{9}nm}[/tex] ⇒ [tex]4x10^{-7}m[/tex]
[tex]\nu = \frac{3x10^{8}m/s}{4x10^{-7}m}[/tex]
[tex]\nu = 7.5x10^{14}Hz[/tex]
Hence, the frequency range of UVA is [tex]7.5x10^{14}Hz[/tex] to [tex]9.37x10^{14}Hz[/tex].
Suppose the Earth orbited the Sun in 4 months rather than 1 year, but had exactly the samerotation speed. How much longer would a solar day be than a sidereal day? Mercury’s siderealday is 58.6 days and its orbital period is 88 days. What is the length of Mercury’s solar day?
Answer:
A) 0.1955 days
B) 35.18 days
Explanation: Given that the Earth orbited the Sun in 4 months rather than 1 year, but had exactly the same rotation speed. That is the orbital period will be
365.24/12 = P/4
P = 121.75 days
We have three periods, the orbital period Po = 121.75 days,
the sidereal period Ps = 23.93419 hours and
The mean solar day Pd =24 hours.
Since they had exactly the same rotation speed, the number of solar days in a year is Po/Pd.
The number of sidereal days in a year would be Po/Pd + 1 = 121.75 + 1 = 122.75 days. Since there are more sidereal days in a year this means that the sidereal day is a little bit shorter, 121.75/122.75 = 0.99185 times shorter.
0.99185 × 24 = 23.80448 hours.
24 - 23.80448 = 0.1955 days
Therefore, solar day is 0.99185 days longer than a sidereal day
Given that the Mercury’s side real day is 58.6 days and its orbital period is 88 days. What is the length of Mercury’s solar day?
Using the formula
Ld = PoPs/(Po + Ps)
Ld = Length of Mercury's solar day
Po = orbital period
Ps = Mercury's side real day
Ld = (88 × 58.6)/ (88 + 58.6)
Ld = 5156.8/146.6
Ld = 35.18 days
Space satellites in the inner solar system (such as those in orbit around Earth) are often powered by solar panels. Satellites that travel into the outer solar system, however, are usually powered by the decay of nuclear isotopes – a more expensive and dangerous technology. Why can’t they use solar panels as well?
a. At greater distances, sunlight is more likely to destructively interfere.
b. At greater distances, sunlight is more likely to constructively interfere.
c. At greater distances from the sun, the frequency of sunlight will be too low.
d. At greater distances from the sun, the intensity of sunlight will be too low.
Answer:
D
Explanation:
See attached file
The same pipe is used to carry both air and water. For the same fluid velocity and friction factor for the air and water flows: the pressure drop for the air flow is greater than that for the water flow. the pressure drop for the air flow equals the pressure drop for the water flow. the pressure drop for the water flow is greater than that for the air flow.
Answer:
the pressure drop for the water flow is greater than that for the air flow.
Explanation:
Detailed analysis of the problem is show below.