Answer:
A. 20 Watts
Explanation:
Power is the rate of doing work.
P = Fd/t = (15 N)(8 m)/(6 s) = 20 N·m/s = 20 W
20 watts. If the power of the man who pushes the box 8m with a force of 15n is 6 seconds, it will force 20 watts in 6 seconds.
First, you do is multiply and then divide to give us the final answer.
[tex]\displaystyle 8m\times15n\div6s[/tex]
[tex]\displaystyle 8\times15=120\div6=20[/tex]
[tex]\Large\boxed{20}[/tex], which is our answer.
Why are noise considerations important in optical fiber communications? 3. Describe the principle of "population inversion".
Answer and Explanation:
the electronic devices always have some noises present in the signal
there are some important considerations in optical fiber communications these are.
the noise which is contributed by transmitter are electronic random noise, low frequency noisenoise which is contributed by laser are relative intensity noise, mode partition noise, conversion of phase noise to amplitude noise.noise contributed by photo detector are quantum shot noise, shot noise from dark current, avalanche multiplication noise.PRINCIPLE OF POPULATION INVERSION :
The principle of population inversion is defined as for production of high percentage of simulated emission for a laser beam the number of atoms in higher state should be greater than lower energy state
Noise considerations are important in optical fiber communications to maintain the fidelity of the transmitted signal. Population inversion, a critical principle for laser operation, involves achieving more particles in an excited state than in a lower energy state. Single frequency operation and the prevention of multiple transverse modes result in a more focused beam for optimal transmission.
Noise considerations are crucial in optical fiber communications because they can affect the fidelity and integrity of the transmitted signal. Noise can result from a variety of sources, including intrinsic factors within the fiber, like Rayleigh scattering, or from external influences such as electromagnetic interference. Managing noise is essential to maintain a high signal-to-noise ratio (SNR), which enables the clear and accurate transmission of data over long distances.
The principle of population inversion is critical to the functioning of lasers, which are the light sources commonly used in optical fiber communication. Population inversion occurs when a system has more particles in an excited state than in a lower energy state, which is normally the opposite of what happens in thermal equilibrium. It can be achieved by pumping the system with energy, which propels the electrons into a higher energy level. Once the system has achieved population inversion, stimulated emission can occur, leading to the amplification of light and allowing for laser emission.
In laser systems, single frequency operation is often desired, which can be obtained through various methods such as using a monochromatic light source or employing optical filters. Regarding transverse modes, these are the different patterns of light intensity distribution across the cross-section of the beam. Preventing multiple transverse modes ensures that the laser operates in a single spatial mode, providing a cleaner and more focused beam, which is ideal for optical fiber transmissions.
An element has the following natural abundances and isotopic masses: 90.92% abundance with 19.99 amu, 0.26% abundance with 20.99 amu, and 8.82% abundance with 21.99 amu. Calculate the average atomic mass of this element.
Answer: The average atomic mass of the given element is 20.169 amu.
Explanation:
Average atomic mass of an element is defined as the sum of masses of the isotopes each multiplied by their natural fractional abundance.
Formula used to calculate average atomic mass follows:
[tex]\text{Average atomic mass }=\sum_{i=1}^n\text{(Atomic mass of an isotopes)}_i\times \text{(Fractional abundance})_i[/tex] .....(1)
We are given:
For isotope 1:Mass of isotope 1 = 19.99 amu
Percentage abundance of isotope 1 = 90.92 %
Fractional abundance of isotope 1 = 0.9092
For isotope 2:Mass of isotope 2 = 20.99 amu
Percentage abundance of isotope 2 = 0.26%
Fractional abundance of isotope 2 = 0.0026
For isotope 3:Mass of isotope 3 = 21.99 amu
Percentage abundance of isotope 3 = 8.82%
Fractional abundance of isotope 3 = 0.0882
Putting values in equation 1, we get:
[tex]\text{Average atomic mass}=[(19.99\times 0.9092)+(20.99\times 0.0026)+(21.99\times 0.0882)][/tex]
[tex]\text{Average atomic mass}=20.169amu[/tex]
Hence, the average atomic mass of the given element is 20.169 amu.
A proton initially at rest is accelerated by a uniform electric field. The proton moves 5.62 cm in 1.15 x 10^-6 s. Find the voltage drop through which the proton moves. (Answer should be positive)
Answer:
49.85 V
Explanation:
u = 0, s = 5.62 cm, t = 1.15 x 10^-6 s
Let the electric field is E and voltage is V.
Use second equation of motion
s = ut + 1/2 a t^2
5.62 x 10^-2 = 0 + 0.5 a x (1.15 x 10^-6)^2
a = 8.5 x 10^10 m/s^2
m x a = q x E
E = m x a / q
E = (1.67 x 10^-27 x 8.5 x 10^10) / (1.6 x 10^-19)
E = 887.19 V/m
V = E x s
V = 887.19 x 5.62 x 10^-2 = 49.85 V
Calculate the mass of the air contained in a room that measures 2.50 m x 5.50 m x 3.00 m if the density of air is 1.29 g/dm3.53.2 g3.13 x 10-3 g3.20 x 104 g5.32 x 104 g5.32 x 107 g
Answer:
[tex]5.32\cdot 10^4 g[/tex]
Explanation:
First of all, we need to find the volume of the room, which is given by
[tex]V=2.50 m \cdot 5.50 m \cdot 3.00 m =41.3 m^3[/tex]
Now we can find the mass of the air by using
[tex]m=dV[/tex]
where
[tex]d=1.29 g/dm^3[/tex] is the density of the air
[tex]V=41.3 m^3 = 41,300 dm^3[/tex] is the volume of the room
Substituting,
[tex]m=(1.29)(41300)=5.32\cdot 10^4 g[/tex]
Final answer:
The mass of the air in a room with dimensions 2.50 m x 5.50 m x 3.00 m and an air density of 1.29 g/dm³ is calculated to be 53.2 kg.
Explanation:
The mass of the air in the room can be calculated by using the formula for density, which is mass (mass) equals density (density) times volume (volume), or m = ρV. Given that the density of air is 1.29 g/dm³, first we need to convert the measurements of the room to dm³ (decimeters cubed) as the given room dimensions are in meters. The volume of the room is 2.50 m x 5.50 m x 3.00 m which equals 41.25 m³. Converting from cubic meters to cubic decimeters results in 41,250 dm³ (1 m³ = 1,000 dm³). Therefore, the mass of air is calculated as 1.29 g/dm³ * 41,250 dm³, which equals 53,212.5 grams or 53.2 kg.
Star A has a radius of 200 000 km and a surface temperature of 6 000 K. Star B has a radius of 400 000 km and a surface temperature of 3 000 K. The emissivity of both stars is the same. What is the ratio of the rate of energy radiated by Star A to that of Star B?
Explanation:
In order to solve this problem, the Stefan-Boltzmann law will be useful. This law establishes that a black body (an ideal body that absorbs or emits all the radiation that incides on it) "emits thermal radiation with a total hemispheric emissive power proportional to the fourth power of its temperature":
[tex]P=\sigma A T^{4}[/tex] (1)
Where:
[tex]P[/tex] is the energy radiated by a blackbody radiator per second, per unit area (in Watts).
[tex]\sigma=5.6703(10)^{-18}\frac{W}{m^{2} K^{4}}[/tex] is the Stefan-Boltzmann's constant.
[tex]A[/tex] is the Surface of the body
[tex]T[/tex] is the effective temperature of the body (its surface absolute temperature) in Kelvin.
However, there is no ideal black body (although the radiation of stars like our Sun is quite close). Therefore, we will use the Stefan-Boltzmann law for real radiator bodies:
[tex]P=\sigma A \epsilon T^{4}[/tex] (2)
Where [tex]\epsilon[/tex] is the star's emissivity
Knowing this, let's start with the answer:
We have two stars where the emissivity [tex]\epsilon[/tex] of both is the same:
Star A with a radius [tex]r_{A}=200000km[/tex] and a surface temperature [tex]T_{A}=6000K[/tex].
Star B with a radius [tex]r_{B}=400000km[/tex] and a surface temperature [tex]T_{B}=3000K[/tex].
And we are asked to find the ratio of the rate of energy radiated by both stars:
[tex]\frac{P_{A}}{P_{B}}[/tex] (3)
Where [tex]P_{A}[/tex] is the rate of energy radiated by Star A and [tex]P_{B}[/tex] is the rate of energy radiated by Star B.
On the other hand, with the radius of each star we can calculate their surface area, using the formula for tha area of a sphere (assuming both stars have spherical shape):
[tex]A_{A}=4\pi r_{A}^{2}[/tex] (4)
[tex]A_{B}=4\pi r_{B}^{2}[/tex] (5)
Writting the Stefan-Boltzmann law for each star, taking into consideration their areas:
[tex]P_{A}=\sigma (4\pi r_{A}^{2}) \epsilon {T_{A}}^{4}[/tex] (6)
[tex]P_{B}=\sigma (4\pi r_{B}^{2}) \epsilon {T_{b}}^{4}[/tex] (7)
Substituting (6) and (7) in (3):
[tex]\frac{\sigma (4\pi r_{A}^{2}) \epsilon {T_{A}}^{4}}{\sigma (4\pi r_{B}^{2}) \epsilon {T_{B}}^{4}}[/tex] (8)
[tex]\frac{P_{A}}{P_{B}}=\frac{{r_{A}}^{2} {T_{A}}^{4}}{{r_{B}}^{2} {T_{B}}^{4}}[/tex] (9)
[tex]\frac{P_{A}}{P_{B}}=\frac{{(200000km)}^{2} {(6000K)}^{4}}{{(400000km)}^{2} {(3000K)}^{4}}[/tex] (10)
Finally:
[tex]\frac{P_{A}}{P_{B}}=4[/tex]
A Carnot heat engine has an efficiency of 0.200. If it operates between a deep lake with a constant temperature of 293.0 K and a hot reservoir, what is the temperature of the hot reservoir? O 352 K O 1760 K O 366 K 1470 K
Answer:
366 K
Explanation:
T₀ = Constant Temperature of deep lake = 293.0 K
T = Temperature of hot reservoir connected to carnot engine = ?
η = Efficiency of Carnot engine during the operation
Efficiency of Carnot engine is given as
[tex]\eta = 1-\frac{T_{o}}{T}[/tex]
Inserting the values
[tex]0.200 = 1-\frac{293.0}{T}[/tex]
T = 366 K
An artificial satellite is in a circular orbit around a planet of radius r= 2.05 x103 km at a distance d 310.0 km from the planet's surface. The period of revolution of the satellite around the planet is T 1.15 hours. What is the average density of the planet?
Answer:
[tex]\rho = 12580.7 kg/m^3[/tex]
Explanation:
As we know that the satellite revolves around the planet then the centripetal force for the satellite is due to gravitational attraction force of the planet
So here we will have
[tex]F = \frac{GMm}{(r + h)^2}[/tex]
here we have
[tex]F =\frac {mv^2}{(r+ h)}[/tex]
[tex]\frac{mv^2}{r + h} = \frac{GMm}{(r + h)^2}[/tex]
here we have
[tex]v = \sqrt{\frac{GM}{(r + h)}}[/tex]
now we can find time period as
[tex]T = \frac{2\pi (r + h)}{v}[/tex]
[tex]T = \frac{2\pi (2.05 \times 10^6 + 310 \times 10^3)}{\sqrt{\frac{GM}{(r + h)}}}[/tex]
[tex]1.15 \times 3600 = \frac{2\pi (2.05 \times 10^6 + 310 \times 10^3)}{\sqrt{\frac{(6.67 \times 10^{-11})(M)}{(2.05 \times 10^6 + 310 \times 10^3)}}}[/tex]
[tex]M = 4.54 \times 10^{23} kg[/tex]
Now the density is given as
[tex]\rho = \frac{M}{\frac{4}{3}\pi r^3}[/tex]
[tex]\rho = \frac{4.54 \times 10^{23}}{\frac{4}[3}\pi(2.05 \times 10^6)^3}[/tex]
[tex]\rho = 12580.7 kg/m^3[/tex]
After falling from rest at a height of 32.3 m, a 0.556 kg ball rebounds upward, reaching a height of 22.1 m. If the contact between ball and ground lasted 1.62 ms, what average force was exerted on the ball?
Answer:
F = 15771.6 N
Explanation:
Initial velocity of ball just before it will collide is given as
[tex]v_i = \sqrt{2gh_1}[/tex]
[tex]v_i = \sqrt{2(9.81)(32.2)}[/tex]
[tex]v_i = 25.13 m/s[/tex]
now for final speed of rebound we have
[tex]v_f = \sqrt{2gh_2}[/tex]
[tex]v_f = \sqrt{2(9.81)(22.1)}[/tex]
[tex]v_f = 20.82 m/s[/tex]
now the average force is given as
[tex]F = \frac{mv_f - mv_i}{\Delta t}[/tex]
[tex]F = \frac{0.556(20.82 + 25.13)}{1.62 \times 10^{-3}}[/tex]
[tex]F = 15771.6 N[/tex]
The gas within a cylinder of an engine undergoes a net change in volume of 1.50 × 10-3 m3 when it does work at a constant pressure of 3.27 x 105 Pa If the efficiency of the engine is 0.225, how much work must the engine give up as heat to the low-temperature reservoir?
Answer:
work =p×v =3.27×10^5×1.5×10^-3 =490.5 joule
efficiency =w/q in
:. qin= w/efficiency =490.5/0.225=2180 joule
qout =q in - work =1689.5 joule
q out is work given as heat
The engine must give up 1689.5 J of heat to the low-temperature reservoir after calculating the total work done by the gas and accounting for the engine's efficiency.
To find the amount of work the engine gives up as heat, we first calculate the total work done by the gas using the formula W = PΔV, where W is work, P is pressure, and ΔV is the change in volume. Given a constant pressure of 3.27 x 105 Pa and a change in volume of 1.50 x 10-3 m3, the work done is:
W = PΔV = 3.27 x 105 Pa x 1.50 x 10-3 m3 = 490.5 J.
The efficiency of the engine is the ratio of the useful work output to the total work input, given by ext_eta = useful work / total work. The equation that relates efficiency, work done (W), and heat given up (Q) is ext_eta = W / (Q + W). We rearrange the equation to solve for Q:
Q = W / ext_eta - W
Substituting the known values:
Q = 490.5 J / 0.225 - 490.5 J = 2180 J - 490.5 J = 1689.5 J.
Therefore, the engine must give up 1689.5 J of heat to the low-temperature reservoir.
A 26.2-kg dog is running northward at 3.21 m/s, while a 5.30-kg cat is running eastward at 2.64 m/s. Their 67.2-kg owner has the same momentum as the two pets taken together. Find the direction and magnitude of the owner's velocity.
The owner's velocity, with the same momentum as the combined momentum of the dog and cat, is 1.28 m/s directed 9.46 degrees east of the north.
Explanation:To solve this problem, we need to calculate the dog's momentum, the cat's momentum, and then use these two results to find the owner's velocity and direction.
First, let's calculate the momentum for each pet. Momentum (p) is defined as mass (m) times velocity (v). For the dog, p = mv = 26.2 kg * 3.21 m/s = 84.042 kg*m/s northward. For the cat, p = mv = 5.30 kg * 2.64 m/s = 13.992 kg*m/s eastward.
To find the combined momentum vector of the two animals, we will use Pythagorean theorem because the vectors are perpendicular to each other. So, resultant momentum = sqrt[(84.042^2) + (13.992^2)] = 85.87 kg*m/s.
The owner's momentum equals the total momentum of the dog and cat, so that's 85.87 kg*m/s. The magnitude of the owner's velocity (v) is therefore the momentum divided by his mass: v = p / m = 85.87 kg*m/s / 67.2 kg = 1.28 m/s. The direction of the owner's velocity can be found using trigonometry. The angle is arctan (cat's momentum / dog's momentum) = arctan (13.992 / 84.042) = 9.46° east from north.
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The magnitude of the owner's velocity is approximately [tex]\( 1.267 \, \text{m/s} \)[/tex], and the direction is [tex]\( 45^\circ \)[/tex] northeast.
To find the direction and magnitude of the owner's velocity, we need to calculate the total momentum of the dog and cat and then equate that to the owner's momentum.
First, we calculate the momentum of the dog and cat separately using the formula p = mv , where p is the momentum, m is the mass, a v is the velocity.
For the dog:
[tex]\[ p_{\text{dog}} = m_{\text{dog}} \times v_{\text{dog}} \][/tex]
[tex]\[ p_{\text{dog}} = 26.2 \, \text{kg} \times 3.21 \, \text{m/s} \][/tex]
[tex]\[ p_{\text{dog}} = 84.002 \, \text{kg} \cdot \text{m/s} \][/tex]
For the cat:
[tex]\[ p_{\text{cat}} = m_{\text{cat}} \times v_{\text{cat}} \][/tex]
[tex]\[ p_{\text{cat}} = 5.30 \, \text{kg} \times 2.64 \, \text{m/s} \][/tex]
[tex]\[ p_{\text{cat}} = 14.032 \, \text{kg} \cdot \text{m/s} \][/tex]
The total momentum of the dog and cat is the vector sum of their individual momenta. Since they are moving in perpendicular directions (northward and eastward), we can use the Pythagorean theorem to find the magnitude of the total momentum:
[tex]\[ p_{\text{total}} = \sqrt{p_{\text{dog}}^2 + p_{\text{cat}}^2} \][/tex]
[tex]\[ p_{\text{total}} = \sqrt{(84.002)^2 + (14.032)^2} \][/tex]
[tex]\[ p_{\text{total}} = \sqrt{7056.0624 + 196.82784} \][/tex]
[tex]\[ p_{\text{total}} = \sqrt{7252.89} \][/tex]
[tex]\[ p_{\text{total}} \ =85.136 \, \text{kg} \cdot \text{m/s} \][/tex]
The direction of the total momentum vector is northeast, which is [tex]45^\circ \)[/tex] from the northward direction (the direction of the dog's velocity).
Now, we equate the owner's momentum to the total momentum of the pets:
[tex]\[ p_{\text{owner}} = p_{\text{total}} \][/tex]
[tex]\[ m_{\text{owner}} \times v_{\text{owner}} = p_{\text{total}} \][/tex]
[tex]\[ 67.2 \, \text{kg} \times v_{\text{owner}} = 85.136 \, \text{kg} \cdot \text{m/s} \][/tex]
[tex]\[ v_{\text{owner}} = \frac{85.136 \, \text{kg} \cdot \text{m/s}}{67.2 \, \text{kg}} \][/tex]
[tex]\[ v_{\text{owner}} \ = 1.267 \, \text{m/s} \][/tex]
Stress distributed over an area is best described as: a) External force b) Axial force c) Radial force d) Internal resistive force none of these e
Answer:
Option D is the correct answer.
Explanation:
Stress is the force per unit area that tend to change the shape of body.
Stress is defined as internal resistive force per unit area.
[tex]\texttt{Stress}=\frac{\texttt{Internal resistive force}}{\texttt{Area}}[/tex]
[tex]\sigma =\frac{F}{A}[/tex]
So, so stress distributed over an area is best described as internal resistive force.
Option D is the correct answer.
Final answer:
Stress distributed over an area refers to the internal resistive forces that develop within a material in response to applied external forces. It is best described as an internal force, specifically termed internal resistive force, and is measured as the force per unit area.
Explanation:
Stress distributed over an area is best described as d) Internal resistive force. Stress is a physical quantity that represents the internal forces per unit area within a material that develop as a response to applied external forces or changes in temperature. It is calculated by the ratio of force to area and measured in Newtons per square meter (N/m²). Stress caused by forces perpendicular to the cross-section of the material is called normal stress, which can be tensile or compressive. Similarly, stress caused by forces parallel to the area, such as shear stress, represents deformation through sliding layers.
For example, when a metal rod is pulled from both ends, the internal resistive forces that develop within the material to oppose elongation are a manifestation of tensile stress. In contrast, when a book is pushed down upon by a hand, the internal resistive forces that prevent the book from compressing are an example of compressive stress.
While on a moving elevator during a certain perfod or time, Frank's apparent weight is 620 N. If Frank's mass is 70 kg, what is the magnitude and direction of Frank's acceleration?
Answer:
0.94 m/s^2 downwards
Explanation:
m = 70 kg, m g = 70 x 9.8 = 686 N
R = 620 N
Let the acceleration be a, as the apparent weight decreases so the elevator is moving downwards with an acceleration a.
mg - R = ma
686 - 620 = 70 x a
a = 0.94 m/s^2
A circular coil has a radius r and N turns and is in a uniform magnetic field that depends only on time, B = B(t). The angle of the coil is θ to the direction of the field and the total curcuit has resistance R. Find an expression for the current I.
Answer:
(N x π x r^2 x Cosθ) / R x dB(t) / dt
Explanation:
radius = r , Number of turns = N, B = B(t), Angle = θ, Resistance = R
induced emf = rate of change of magnetic flux
e = - N x dΦ / dt
e = - N x d(B A Cosθ) / dt
e = - N x A x Cosθ x dB(t) / dt
e = - N x π x r^2 x Cosθ x dB(t) / dt
where, negative sign shows the direction of induced emf in the coil.
induced current, i = induced emf / resistance
i = - (N x π x r^2 x Cosθ) / R x dB(t) / dt
You are looking up at the top of a building at an angle of 30.6 degrees from the horizontal. If the building is 42.0m tall, how far are you from the building? Assume that you are 1.50m tall.
Answer:
The distance between the person and the building is 68.48 meters.
Explanation:
It is given that,
Angle of elevation, θ = 30.6 degrees
Height of building, MP = 42 m
Height of person, AB = 1.5 m
We need to find the distance between person and building. It is given by BP.
Since, MN + NP = 42
So, MN = 40.5 m
Using trigonometric equation as :
[tex]tan\theta=\dfrac{MN}{AN}[/tex]
[tex]tan(30.6)=\dfrac{40.5}{AN}[/tex]
AN = 68.48 meters.
So, the distance between the person and the building is 68.48 meters. Hence, this is the required solution.
To determine the distance from a building, we use trigonometry and the formula adjacent = opposite / tangent(angle), taking into account the height of the building minus your height. The distance is calculated to be approximately 68.88 meters.
Explanation:To find out how far you are from the building, we need to calculate the horizontal distance from the building's base to the point where you are standing. To do this, we can use trigonometry, specifically the tangent function which relates the angle of elevation to the opposite side and the adjacent side of a right-angle triangle. We need to consider the height of the building minus your height to find the correct opposite side.
Since the building is 42.0 meters tall, and you are 1.50 meters tall, the effective height we are looking at is 42.0 m - 1.50 m = 40.5 m. The angle of elevation you are looking at is 30.6 degrees. By using the formula tangent (angle) = opposite / adjacent, we can rearrange this to find the adjacent side (the distance from you to the building): adjacent = opposite / tangent (angle).
Therefore, the distance from you to the building is approximately adjacent = 40.5 m / tan(30.6°). Plugging in the values, we get:
Distance = 40.5 m / tan(30.6°) ≈ 40.5 m / 0.588 ≈ 68.88 m.
So, you are approximately 68.88 meters away from the building.
Suppose a woman does 500 J of work and 9500 J of heat transfer occurs into the environment in the process. (a) What is the decrease in her internal energy, assuming no change in temperature or consumption of food? (That is, there is no other energy transfer.) (b) What is her efficiency?
Answer:
The change in internal energy and efficiency are 10000 J and 5.26%.
Explanation:
Given that,
Work = 500 J
Heat transfer = 9500 J
(a). We need to calculate the decrease in her internal energy
Using equation of internal energy of a system
[tex]\Delta U=Q-W[/tex]
Q = heat
W = work done
Put the value into the formula
She looses her heat -9500 J
[tex]\Delta U=-9500-500[/tex]
[tex]\Delta U=-10000\ J[/tex]
(b). We need to calculate the efficiency
Using formula of efficiency
[tex]e=\dfrac{W}{Q}[/tex]
[tex]e=\dfrac{500}{9500}[/tex]
[tex]e=0.0526\times100[/tex]
[tex]e=5.26\%[/tex]
Hence, The change in internal energy and efficiency are 10000 J and 5.26%.
By using the first law of thermodynamics, we calculate the decrease in the woman's internal energy to be -10000 J as a result of 500 J of work done and 9500 J of heat transfer into the environment. Her efficiency, defined as the ratio of work done to the absolute value of the decrease in internal energy, is found to be 5%.
Explanation:Part (a), let's calculate the decrease in her internal energy. We'll use the first law of thermodynamics, ΔU = Q - W, which stipulates that the change in internal energy (ΔU) in a system is equal to the heat transferred into the system (Q) minus the work done by the system (W). Here, the heat transferred is -9500 J (it's negative since it's transferred out of her body). The work done is 500 J. Hence, the decrease in internal energy is ΔU = -9500 J - 500 J = -10000 J.
For part (b), efficiency (η) is defined as the ratio of the useful output to the total input. In this case, the useful output is the work done, and the total input is the absolute value of the decrease in internal energy. Thus, her efficiency is η = 500 J / 10000 J = 5%.
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A cylindrical blood vessel is partially blocked by the buildup of plaque. At one point, the plaque decreases the diameter of the vessel by 59.0%. The blood approaching the blocked portion has speed V0. Just as the blood enters the blocked portion of the vessel, what is its speed V, expressed as a multiple of V0?
Using the principle of continuity for incompressible fluids, if the diameter of a blood vessel is reduced by 59.0% due to plaque, the speed of the blood just as it enters this section will be approximately 2.44 times its initial speed.
Explanation:The subject of the question falls under the topic of fluid flow in physics, specifically concerning the principle of continuity for incompressible fluids. This principle, often applied in fluid dynamics, suggests that in an area of steadily flowing fluid, the mass passing through one cross-section in a unit of time equals the mass passing through other sections.
Given this principle, if the cross-sectional area of the blood vessel decreases due to plaque buildup, the speed of the blood flow must increase accordingly to maintain a steady flow rate. If the diameter of the vessel decreases by 59.0%, the cross-sectional area A, which is proportional to the square of the diameter (A ~ D²), will be reduced to 0.41 of its original value (because (1 - 59/100)² = 0.41). Therefore, the speed V would be 1/0.41, or approximately 2.44 times the original speed V0.
So, if the blood vessel's diameter is reduced by 59.0%, then just as the blood enters the blocked portion of the vessel, its speed V will be 2.44 times the initial speed V0.
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A solid uniform cylinder of mass 4.1 kg and radius 0.057 m rolls without slipping at a speed of 0.79 m/s. What is the cylinder’s total kinetic energy?
Answer:
The cylinder’s total kinetic energy is 1.918 J.
Explanation:
Given that,
Mass = 4.1 kg
Radius = 0.057 m
Speed = 0.79 m/s
We need to calculate the linear kinetic energy
Using formula of linear kinetic energy
[tex]K.E_{l}=\dfrac{1}{2}mv^2[/tex]
[tex]K.E_{l}=\dfrac{1}{2}\times4.1\times(0.79)^2[/tex]
[tex]K.E_{l}=1.279\ J[/tex]
We need to calculate the rotational kinetic energy
[tex]K.E_{r}=\dfrac{1}{2}\times I\omega^2[/tex]
[tex]K.E_{r}=\dfrac{1}{2}\times\dfrac{1}{2}\times mr^2\times(\dfrac{v}{r})^2[/tex]
[tex]K.E_{r}=\dfrac{1}{4}\times m\times v^2[/tex]
[tex]K.E_{r}=\dfrac{1}{4}\times4.1\times(0.79)^2[/tex]
[tex]K.E_{r}=0.639\ J[/tex]
The total kinetic energy is given by
[tex]K.E=K.E_{l}+K.E_{r}[/tex]
[tex]K.E=1.279+0.639[/tex]
[tex]K.E=1.918\ J[/tex]
Hence, The cylinder’s total kinetic energy is 1.918 J.
An ideal gas at 25.8°C and a pressure 1.20 x 10^5 Pa is in a container having a volume of 1.00 L. (a) Determine the number of moles of gas in the container. (b) The gas pushes against a piston, expanding to twice its original volume, while the pressure falls to atmospheric pressure. Find the final temperature.
Answer:
a) 0.0483 mol
b) 232 °C
Explanation:
Ideal gas law:
PV = nRT
where P is absolute pressure,
V is volume,
n is number of moles,
R is universal gas constant,
and T is absolute temperature.
a) Given:
P = 1.20×10⁵ Pa
V = 1.00 L = 1.00×10⁻³ m³
T = 25.8 °C = 298.95 K
PV = nRT
(1.20×10⁵ Pa) (1.00×10⁻³ m³) = n (8.314 m³ Pa / mol / K) (298.95 K)
n = 0.0483 mol
b) Given:
P = 1.013×10⁵ Pa
V = 2.00 L = 2.00×10⁻³ m³
n = 0.0483 mol
PV = nRT
(1.013×10⁵ Pa) (2.00×10⁻³ m³) = (0.0483 mol) (8.314 m³ Pa / mol / K) T
T = 505.73 K
T = 232 °C
What is the magnitude of the electric field 17.1 cm directly above an isolated 1.83Ã10â5 C charge?
Answer:
Electric field, [tex]E=5.63\times 10^{16}\ N/C[/tex]
Explanation:
Given that,
Charge, [tex]q=1.83\times 10^5\ C[/tex]
We need to find the magnitude of electric field 17.1 cm (0.171 m) above an isolated charge. Electric field at a point is given by :
[tex]E=\dfrac{kq}{r^2}[/tex]
[tex]E=\dfrac{9\times 10^9\times 1.83\times 10^5\ C}{(0.171\ m)^2}[/tex]
[tex]E=5.63\times 10^{16}\ N/C[/tex]
So, the electric field is [tex]5.63\times 10^{16}\ N/C[/tex]. Hence, this is the required solution.
A pendulum with a period of 2.00000 s in one location ⎛ ⎝g=9.80m/s2⎞ ⎠ is moved to a new location where the period is now 1.99796 s. What is the acceleration due to gravity at its new location?
Answer:
9.82 m/s^2
Explanation:
T = 2 s, g = 9.8 m/s^2
T' = 1.99796 s
Let the acceleration due to gravity at new location is g'.
The formula for the time period of simple pendulum is given by
[tex]T = 2\pi \sqrt{\frac{L}{g}}[/tex] .... (1)
here, length of the pendulum remains same.
Now at the new location, let the time period be T'.
[tex]T' = 2\pi \sqrt{\frac{L}{g'}}[/tex] .... (2)
Divide equation (2) by equation (1), we get
[tex]\frac{T'}{T} = \sqrt{\frac{g}{g'}}[/tex]
[tex]\frac{1.99796}{2} = \sqrt{\frac{9.8}{g'}}[/tex]
[tex]0.99796 = {\frac{9.8}{g'}}[/tex]
g' = 9.82 m/s^2
tT9.82 m/s².
What is the time period of pendulum?Pendulum is the body which is pivoted a point and perform back and forth motion around that point by swinging due to the influence of gravity.
The time period of a pendulum is the time taken by it to complete one cycle of swing left to right and right to left.
It can be given as,
[tex]T=2\pi \sqrt{\dfrac{L}{g}}[/tex]
Here, (g) is the gravitational force of Earth and (L) is the length of the pendulum.
The time period of the pendulum with a period of 2 s in one location g=9.80m/s2 can be given as,
[tex]2=2\pi \sqrt{\dfrac{L}{9.8}}\\L=0.996468\rm m[/tex]
Now, this pendulum is move to a new location where the period is now 1.99796 s. Thus, put the value in the above formula as,
[tex]1.99796=2\pi \sqrt{\dfrac{0.996468}{g}}\\g=9.82\rm m/s^2[/tex]
Thus, the acceleration due to gravity at its new location for the pendulum is 9.82 m/s².
Learn more about the time period of pendulum here;
https://brainly.com/question/3551146
An electron moves in a circular path perpendicular to a uniform magnetic field with a magnitude of 1.98 mT. If the speed of the electron is 1.53 107 m/s, determine the following.(a) the radius of the circular path
Answer:
4.4 cm
Explanation:
B = 1.98 mT = 1.98 x 10^-3 T, v = 1.53 x 10^7 m/s, m = 9.1 x 10^-31 kg
q = 1.6 x 10^-19 C
(a) The force due to the magnetic field is balanced by the centrpetal force
mv^2 / r = q v B
r = m v / q B
r = (9,1 x 10^-31 x 1.53 x 10^7) / (1.98 x 10^-3 x 1.6 x 10^-19)
r = 0.044 m = 4.4 cm
Oil is poured into the open side of an open-tube manometer containing mercury. What is the density of the oil if a column of mercury 5.50 cm high supports a column of oil 85.0 cm high? (The density of mercury is 13,600 kg/m³)
Answer:
880 kg / m^3
Explanation:
height of column of oil = 85 cm = 0.85 m
height of column of mercury = 5.5 cm = 0.055 m
Density of mercury = 13600 kg/m^2
Let teh density of oil is d.
A the height of mercury column is balanced by the height of oil column
So, the pressure due to the mercury column = pressure by teh oil column
height of mercury column x density of mercury x g = height of oil column
x density of oil x g
0.055 x 13600 x g = 0.85 x d x g
748 = 0.85 d
d = 880 kg / m^3
Many Amtrak trains can travel at a top speed of 47.0 m/s. Assuming a train maintains that speed for several hours, how many kilometers will the train have traveled after 5.00 hours? Round to the nearest km.
Answer:
846 km
Explanation:
Speed = 47 m/s
time = 5 hours = 5 x 60 x 60 seconds
Distance = speed x time
Distance = 47 x 5 x 60 x 60
Distance = 846000 m
Distance = 846 km
A meter stick is found to balance at the 49.7-cm mark when placed on a fulcrum. When a 50.0-gram mass is attached at the 10.0-cm mark, the fulcrum must be moved to the 39.2-cm mark for balance. What is the mass (in grams) of the meter stick?
Answer:
Mass of the stick = 139.04 gram
Explanation:
Let the mass of the meter stick be = M grams
given:
Attached mass, m = 50.0 gram
position of the fulcrum = 39.2 cm
The meter stick is balanced at 49.7 cm, therefore the center of mass of the stick will be at 49.7 cm
Now for the system to be balanced the moment due to all the masses about the fulcrum must be equal.
thus,
moment = Force × perpendicular distance from the point of movement
Force = mass × acceleration due to gravity(g)
therefore,
(refer figure for the distances)
50g × (39.2-10) = Mg × (49.7 - 39.2)
⇒[tex]M=\frac{50\times 29.2}{10.5}[/tex]
⇒M = 139.04 gram
Calculate the Reynolds number for a person swimming through maple syrup. The density of syrup is about 1400 kg/m^3 and the viscosity is about 0.5 Pa's. A person is about 2m in length and can swim about 1 m/s.
Answer:
The Reynolds number is 5600.
Explanation:
Given that,
Density = 1400 kg/m³
Viscosity = 0.5 Pa's
Length = 2 m
Speed = 1 m/s
We need to calculate the Reynolds number
Using formula of Reynolds number
[tex]R_{e}=\dfrac{\rho V\times L}{\mu}[/tex]
Where, [tex]\rho[/tex] = density of fluid
v = speed of syrup
l = length of a person
[tex]\mu[/tex]=Viscosity
Put the all value into the formula
[tex]R_{e}=\dfrac{1400\times1\times2}{0.5}[/tex]
[tex]R_{e}=5600[/tex]
Hence, The Reynolds number is 5600.
You have a double slit experiment, with the distance between the two slits to be 0.025 cm. A screern is 120 cm behind the double slits. The distance between the central maximum and the Sh maximum is 1.52 cm. Please calculate the wavelength of the light used in the experiment
Answer:
The wavelength of the light is 633 nm.
Explanation:
Given that,
Distance between the two slits d= 0.025 cm
Distance between the screen and slits D = 120 cm
Distance between the slits y= 1.52 cm
We need to calculate the angle
Using formula of double slit
[tex]\tan\theta=\dfrac{y}{D}[/tex]
Where, y = Distance between the slits
D = Distance between the screen and slits
Put the value into the formula
[tex]\tan\theta=\dfrac{1.52}{120}[/tex]
[tex]\theta=\tan^{-1}\dfrac{1.52}{120}[/tex]
[tex]\theta=0.725[/tex]
We need to calculate the wavelength
Using formula of wavelength
[tex]d\sin\theta=n\lambda[/tex]
Put the value into the formula
[tex]0.025\times\sin0.725=5\times\lambda[/tex]
[tex]\lambda=\dfrac{0.025\times10^{-2}\times\sin0.725}{5}[/tex]
[tex]\lambda=6.326\times10^{-7}\ m[/tex]
[tex]\lambda=633\ nm[/tex]
Hence, The wavelength of the light is 633 nm.
A car weighing 11.1 kN and traveling at 13.4 m/s without negative lift attempts to round an unbanked curve with a radius of 61.0 m. (a) What magnitude of the frictional force on the tires required to keep the car f static friction between the tire or not ("yes" or "no")? on its circular If the coefficient ro s 0.35, is the attempt at taking the curve successf (a) Number Units (b)
Answer:
Well..
Explanation:
That's impossible. I know because I once weighed 11.1 kN, and I was temporarily immobile. It's probably the same for a car, and therefore it can not be "traveling" anywhere at all.. unless you put the car on an airplane or a boat or something.
What is the current produced by the solar cells of a pocket calculator through which 4.00 C of charge passes in 4.00 hr? Give your answer in mA.
The average current passing through a device is given by:
I = Q/Δt
I is the average current
Q is the amount of charge that has passed through the device
Δt is the amount of elapsed time
Given values:
Q = 4.00C
Δt = 4.00hr = 14400s
Plug in the values and solve for I:
I = 4.00/14400
I = 0.000277777778A
I = 0.278mA
Final answer:
The current produced by the solar cells of a pocket calculator through which 4.00 C of charge passes in 4.00 hours is 0.278 milliamperes.
Explanation:
The current produced by the solar cells of a pocket calculator when 4.00 C of charge passes through it in 4.00 hours can be calculated using the formula for electric current I = Q / t, where I is the current in amperes, Q is the charge in coulombs, and t is the time in seconds.
To find the current in milliamperes (mA), first convert the time to seconds:
4.00 hours × 3600 seconds/hour = 14400 seconds.
Next, use the formula to calculate current:
I = 4.00 C / 14400 s = 0.00027778 A,
which is equivalent to 0.278 mA
A force F S applied to an object of mass m1 produces an acceleration of 3.00 m/s2. The same force applied to a second object of mass m2 produces an acceleration of 1.00 m/s2. (a) What is the value of the ratio m1/m2? (b) If m1 and m2 are combined into one object, find its acceleration under the action of the force F S .
Answer:
a) [tex]\frac{m_1}{m_2}=\frac{1}{3}[/tex]
b) Acceleration = 0.75 m/s²
Explanation:
a) We have force , F = mass x acceleration.
[tex]\texttt{Value of force}=F_s[/tex]
[tex]\texttt{Acceleration of }m_1=3m/s^2\\\\\texttt{Acceleration of }m_2=1m/s^2[/tex]
We have force value is same
[tex]m_1\times 3=m_2\times 1\\\\\frac{m_1}{m_2}=\frac{1}{3}[/tex]
b) We have
[tex]m_1\times 3=m_2\times 1\\\\m_2=3m_1[/tex]
Combined mass
[tex]m=m_1+m_2=m_1+3m_1=4m_1[/tex]
Force
[tex]F_s=4m_1\times a\\\\a=\frac{F_s}{4m_1}=\frac{1}{4}\times \frac{F_s}{m_1}=\frac{1}{4}\times 3=0.75m/s^2[/tex]
(a) Find the voltage near a 10.0 cm diameter metal sphere that has 8.00 C of excess positive charge on it. (b) What is unreasonable about this result? (c) Which assumptions are responsible?
Answer:
Part a)
[tex]V = 7.2 \times 10^{11} Volts[/tex]
Part b)
this is a large potential which can not be possible because at this high potential the air will break down and the charge on the sphere will decrease.
Part C)
here we can assume the sphere is placed at vacuum so that there is no break down of air.
Explanation:
Part a)
As we know that the potential near the surface of metal sphere is given by the equation
[tex]V = \frac{kQ}{R}[/tex]
here we have
Q = 8 C
R = 10.0 cm
now we have
[tex]V = \frac{(9\times 10^9)(8 C)}{0.10}[/tex]
[tex]V = 7.2 \times 10^{11} Volts[/tex]
Part b)
this is a large potential which can not be possible because at this high potential the air will break down and the charge on the sphere will decrease.
Part C)
here we can assume the sphere is placed at vacuum so that there is no break down of air.
Final answer:
The voltage near a 10.0 cm diameter metal sphere with 8.00 C of excess charge is calculated to be 1.438 x 10^12 V, which is unreasonable due to the high value leading to inevitable discharge. The assumption of an 8.00 C charge on such a small sphere is responsible for this unrealistic result.
Explanation:
Calculating the Voltage near a Charged Sphere
To find the voltage near a 10.0 cm diameter metal sphere with an excess positive charge of 8.00 C, we use the formula V = kQ/r, where V is the voltage, k is Coulomb's constant (8.99 x 10^9 N m^2/C^2), Q is the charge, and r is the radius of the sphere. For a diameter of 10.0 cm, the radius (r) is 0.05 m. Thus, V = (8.99 x 10^9 N m^2/C^2 * 8.00 C) / 0.05 m = 1.438 x 10^12 V.
Unreasonable Voltage
This voltage is extremely high and unreasonable because a metal sphere of that size could not sustain such a high voltage without discharging. The consequence of such a high voltage would include electric breakdown of the air around the sphere, leading to sparks or lightning-like discharges.
Erroneous Assumptions
The assumption responsible for this unreasonable result is the magnitude of charge being considered. An 8.00 C charge on a small metal sphere is significantly larger than what could realistically accumulate on the surface, given the limits of charge density and material breakdown thresholds.