Answer:
Kf = 470 mJ
Explanation:
According the work-energy theorem, the change in the kinetic energy of one object, is equal to the net work done on it.Since the puck is initially at rest, the change is kinetic energy is just the final kinetic energy of the puck.Assuming that the net force is horizontal, and causes a horizontal displacement also, we can find the net work on the puck as follows:[tex]W_{net} = F_{net} * \Delta X = 0.56 N * 0.84 m = 0.47 J = 470 mJ (1)[/tex]
As we have already said, (1) is equal to the final kinetic energy of the puck:⇒ Kf = 470 mJ (2)Michelle and Isabella are ice skating together. Michelle has a mass of 80 kg and Isabella has a mass of 50 kg. Both are at rest and and Isabella pushes of Michelle causing Isabella to move away at a speed of 4.0 m/s. Determine Michelle's speed.
Answer:
2.5 m/s
Explanation:
We assume the skates are positioned so that the motion is essentially frictionless.
Conservation of momentum tells you Michelle's velocity (v) must satisfy ...
∑mv = 0
(80 kg)(v) + (50 kg)(4 m/s) = 0
v = -(50 kg)(4 m/s)/(80 kg) = -2.5 m/s
Michelle's speed is 2.5 m/s in the direction opposite Isabella's.
Answer:
2.5 m/s
Explanation:
A hovercraft is being driven across a lake on a very windy day. The wind exerts a force of 5000 N north on the hovercraft. The propellers driving the hovercraft also exert a force.
What is the net force (to 3.s.f ) on the hovercraft when the force applied to the hovercraft by the propellers is: 10 000 N west
Answer:
The net force on the hovercraft is 11200 N.
Explanation:
Given;
force exerted on the hovercraft by wind, F₁ = 5000 N north
force exerted on the hovercraft by the propeller, F₂ = 10,000 N west
The net force on the hovercraft is calculated as;
[tex]F_{net} = \sqrt{F_1^2 + F_2^2} \\\\F_{net} = \sqrt{5000^2 + 10,000^2} \\\\F_{net} = 11180.34 \ N\\\\F_{net} = 11200 \ N \ (3.s.f)[/tex]
Therefore, the net force on the hovercraft is 11200 N.
Which type of wall would make the best soundproofing for room?
A.
1.0 centimeter thick glass
OB.
two layers of 0.5 centimeter thick glass with 0.5 centimeters of air between them
C.
two layers of 0.5 centimeter thick glass with 0.3 centimeters of vacuum between them
OD.
1.0 centimeter thick steel
Among the options given, the choice that would make the best soundproofing for a room is option C: two layers of 0.5 centimeter thick glass with 0.3 centimeters of vacuum between them.
Soundproofing is achieved by reducing the transmission of sound waves from one side of the wall to the other. In this case, the combination of two layers of glass with a vacuum between them helps to reduce sound transmission effectively.
Glass is a denser material compared to air or vacuum, so it naturally provides some sound insulation. Adding an extra layer of glass creates a barrier that helps to further dampen sound vibrations. The vacuum between the glass layers acts as an additional sound barrier, as sound waves have difficulty propagating through a vacuum due to the absence of a medium for transmission.
On the other hand, a single layer of 1.0 centimeter thick glass (option A) or two layers of 0.5 centimeter thick glass with 0.5 centimeters of air between them (option B) would provide some sound reduction but not as effective as the combination of glass layers with a vacuum in option C.
1.0 centimeter thick steel (option D) would have high density and mass, which could help with sound insulation to some extent. However, steel can still transmit vibrations and might not be as effective as the combination of glass layers with a vacuum in option C for soundproofing a room.
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Does light travel faster in seawater or in fresh water? Does light travel faster in seawater or in fresh water? Light travels faster in seawater, because the index of refraction is smaller in seawater. Light travels faster in fresh water, because the index of refraction is smaller in fresh water. Light travels faster in fresh water, because the index of refraction is larger in fresh water. Light travels faster in seawater, because the index of refraction is larger in seawater.
No
because that is a light
The light travel faster in fresh water as compare to sea water.
When light goes from denser to rare medium the speed of light is increases.When light travel from rare to denser medium the speed of light is decreases.The reflective index of denser medium is more as compare to rare medium.The reflective index of sea water is more as compare to fresh water.Hence, the light travel faster in fresh water as compare to sea water.
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The other name of eureka can
Answer:
I found it!
Explanation:
Answer:
Explanation:
displacement vessels
The can is filled to the top with water and the object placed in it. The volume of the object is equal to the volume of the water that is forced through the spout. Eureka cans are named after a scientist called Archimedes who first recorded this idea. They are sometimes also called displacement vessels.
An upward force of 32.6 N is applied via a string to lift a ball with a mass of 2.8 kg. (a) What is the gravitational force acting on the ball? (b) What is the net force acting upon the ball? (c) What is the acceleration of the ball?
Answer:
a) Fg = -27.4 N
b) Fnet = 5.2 N
c) a = 1.9 m/s2
Explanation:
a)
There are two forces acting on the ball, one directed upward (assuming this direction as positive, along the y-axis) which is the tension on the string (lifting force), and another aimed downward, which is the attractive force due to gravity.Applying the Newton's Universal Law of Gravitation to a mass close to the surface of the Earth (in this case the ball), we can take the acceleration due to gravity like a constant, that we call by convention g, equal to -9.8 m/s2.So, we can write the following expression for Fg:[tex]F_{g} = m*g = 2.8 kg*(-9.8m/s2) = -27.4 N (1)[/tex]
b)
The net force on the ball, will be just the difference between the lifting force (32.6 N) and the force due to gravity, Fg:[tex]F_{net} = T -F_{g} = 32.6 N - 27.4 N = 5.2 N (2)[/tex]
c)
According Newton's 2nd Law, the acceleration caused by a net force on a point mass (we can take the ball as one) is given by the following expression:[tex]a = \frac{F_{net} }{m} = \frac{5.2N}{2.8kg} = 1.9 m/s2 (3)[/tex]
If the mass of a basketball is 18 times that of a tennis mass, can they ever have the same momentum? Explain your answer
Answer:
Yes
Explanation:
Yes. The momentum is the same when the speed of the tennis ball is 18 times greater than the speed of the basketball and the velocities of both objects are in the same direction.
A 45.0-kg girl stands on a 13.0-kg wagon holding two 18.0-kg weights. She throws the weights horizontally off the back of the wagon at a speed of 6.5 m/s relative to herself . Assuming that the wagon was at rest initially, what is the speed of the girl relative to the ground after she throws both weights at the same time
Answer:
v = 4.0 m/s
Explanation:
Assuming no external forces acting during the instant that the girl throws the weights, total momentum must be conserved.Since all the masses at rest initially, the initial momentum must be zero.So, due to momentum must keep constant, final momentum must be zero too, as follows:[tex]p_{f} = m_{w} * v_{w} + m_{g+w} *v_{g+w} = 0 (1)[/tex]
Assuming the direction towards the back of the wagon as positive, and replacing the masses in (1), we can solve for vg, as follows:[tex]v_{g+w} =- \frac{m_{w} *v_{w}}{m_{g+w} } = - \frac{36.0kg *6.5m/s}{58.0kg } = -4.0m/s (2)[/tex]
This means that the girl (along with the wagon on she is standing) will move at a speed of 4.0 m/s in an opposite direction to the one she threw the weights.You want to see how your new belt buckle matches your new hat. Your eyes are 114 mm below the top of the hat and 800 mm above the buckle. You walk up to your mirror and notice that the mirror is exactly large enough and exactly in the right position for you see both the top of the hat and the buckle.
1. What is the position of the top edge of the mirror relative to your eyes?2. How tall is the mirror?
Answer:
[tex]x=0.057m[/tex]
[tex]h=0.457m[/tex]
Explanation:
From the question we are told that
Distance of eyes from the top of hat [tex]d_1=114mm[/tex]
Distance of eyes from buckle [tex]d_2=800mm[/tex]
Generally position of mirror relative eyes x is mathematically given as
[tex]x=\frac{114}{2}[/tex]
[tex]x=57mm[/tex]
[tex]x=0.057m[/tex]
Generally the height of the mirror h is mathematically given as
[tex]h=\frac{(Buckle\ below\ the\ hat)+(Buckle\ below\ the\ hat)}{2}[/tex]
[tex]h=\frac{(114)+(800)}{2}[/tex]
[tex]h=457mm[/tex]
[tex]h=0.457m[/tex]
PLEASE PLEASE PLEASE HELP
Answer:
just use y = mx + b to create an equation of the line in the graph.
then you can plug in 15 for x and then convert 1.5 hours into minutes and plug it in as well.
you dont even need to make an equation for a line. just add 0.2 for every 3 mins.
at 9, it's 0.6, so at 12 it would be 0.8, and then 15 it would be 1.0.
go again all way for 1. 5 hours.
Explanation:
the slope is 0.1/1.5 so you equation would be y = 0.1/1.5x
the slope is rise/run.
A fox locates its prey under the snow by slight sounds rodents make. The fox then leaps straight into the air, and then burrows its nose into the snow to catch its meal. If a fox jumps up to a height of 79 cm, calculate (a) the speed at which the fox leaves the snow, and (b) how long the fox is in the air. Ignore air resistance.m/s:s:You throw a baseball directly upward at time t = 0 at an initial speed of 12.9 m/s. What is the maximum height the ball reaches above where it leaves your hand? At what times does the ball pass through half the maximum height? Ignore air resistance and take g = 9.80 m/s2.Maximum height:Earlier time at half maximum height:Later time at half maximum height:
Answer:
1.a) 3.93 m/s
b) 0.80 s
2. a) 8.49 m
b) 0.39 s
Explanation:
1. a) The speed at which the fox leaves the snow can be found as follows:
[tex] v_{f}^{2} = v_{0}^{2} - 2gH [/tex]
Where:
g: is the gravity = 9.80 m/s²
[tex]v_{f}[/tex]: is the final speed = 0 (at the maximum height)
[tex]v_{0}[/tex]: is the initial speed =?
H: is the maximum height = 79 cm = 0.79 m
[tex] v_{0} = \sqrt{2gH} = \sqrt{2*9.80 m/s^{2}*0.79 m} = 3.93 m/s [/tex]
Hence, the speed at which the fox leaves the snow is 3.93 m/s.
b) The time at which the fox reaches the maximum height is given by:
[tex]v_{f} = v_{0} - gt[/tex]
[tex]t = \frac{v_{0} - v_{f}}{g} = \frac{3.93 m/s}{9.80 m/s^{2}} = 0.40 s[/tex]
Now, the time of flight is:
[tex] t_{v} = 2t = 2*0.40 s = 0.80 s [/tex]
2. a) The maximum height the ball reaches is:
[tex] H = \frac{v_{0}^{2} - v_{f}^{2}}{2g} = \frac{(12.9 m/s)^{2}}{2*9.80 m/s^{2}} = 8.49 m [/tex]
Then, the maximum height is 8.49 m.
b) The time at which the ball passes through half the maximum height is:
[tex]y_{f} = y_{0} + v_{0}t - \frac{1}{2}gt^{2}[/tex]
Taking y₀ = 0 and [tex]y_{f}[/tex] = 8.49/2 = 4.245 m we have:
[tex] 4.245 m -12.9m/s*t + \frac{1}{2}*9.80m/s^{2}*t^{2} = 0 [/tex]
By solving the above quadratic equation we have:
t = 0.39 s
Therefore, the time at which the ball passes through half the maximum height when the ball is going up is 0.39 s.
I hope it helps you!
A cube has a density of 1800 kg/m3 while at rest in the laboratory. What is the cube's density as measured by an experimenter in the laboratory as the cube moves through the laboratory at 89.0 % of the speed of light in a direction perpendicular to one of its faces?
Answer:
3947.7 kg/m³
Explanation:
The relativistic density can be calculated using below expression;
ρ = ρ' /[√( 1 - v²/c²)]
where,
ρ = Change in Density as a result of motion
ρ'= Actual density of cube
ρ' is given as = 1800 kg/m³
v = Velocity that the cube moves = 0.89c
c = Speed of light
c= 3×10^8 m/s
ρ = ρ' /[√( 1 - v²/c²)]
if we substitute the given values we have
ρ= 1800/ √ 〈1- 0.89c²/ c²〉
ρ=3947.7 kg/m³
Hence, the cube's density is 3947.7 kg/m³
How do I find the specific heat?
I know that
Q= m x c x difference in T
Q= 1.61
M= 476
C=?
Difference in temperature = 20
Answer:
Hope it may help you have a great day at school bye bye. Plz put it in brainliest answer my only request plz plz plz plz plz
Explain why objects in water appear to be a different size then the same objects above the water.
Answer:
the answer is the third one since water reflects it
Explanation:
Suppose two skiers (A and B) are racing. Assume a frictionless surface! They start from the top of a mountain at the same time, and glide down to the flat area below. Just before the finish line there is a ditch. The skiers can either go down into the ditch or take a flat bridge over the ditch. Both the bridge and the ditch are covered with frictionless snow. Skier A decides to go down into the ditch. Skier B decides to go over the bridge. . Which skier gets to the finish line first, or do they arrive at the same time?
a. Skier A (ditch) arrives first
b. Skier B (bridge) arrives first
c. The skiers arrive at the same time
d. Neither skier arrives at the finish line
Answer:
b. Skier B (bridge) arrives first
Explanation:
This is because, skier B continues along the bring with the same velocity he started with before moving over the bridge and since the bridge is frictionless, he losses no kinetic energy and his speed is constant.
Whereas, skier A losses kinetic energy as he goes into the ditch. This is due to his change in potential energy. He thus emerges from the ditch with lesser kinetic energy than skier B and thus a slower speed.
Therefore, skier B arrives first since he moves at a constant speed.
Variables like velocity and acceleration that have both size and direction are called:
a independent. b vectors. c dependent. d axes
models are frequently used in science to assist in the understanding of complex information. Models can include items like a working volcano, and aquarium, or a stream table. What type of model are each of these items?
A) two dimensional
b) three dimensional
c) mental explanation
d) Computer simulation
Two people are playing tug-of-war. Due to their choice of footwear, theircoefficient of static friction is different. Participant 1 has a mass of 60 kg, acoefficient of static friction of 2.0, and can pull with a maximum force of1000 N. Participant 2 has a mass of 80 kg and a coefficient of staticfriction of 1.2, and can pull with a maximum force of 1200 N. Who wins?
Answer:
Participant 1 wins
Explanation:
Coefficient of static, μ = F/N, where F is the frictional force and N is the normal force.
The force exerted by each participant is the sum of the frictional force acting on each of them and the maximum force with which each participant pulls on the rope.
Frictional force, F = μ * N
Normal force, N = mass * acceleration due to gravity, g
For Participant 1; μ = 2.0, mass = 60 kg, g = 9.8 m/s²
Frictional force = 2.0 * 60 * 9.8 = 1176 N
Total force = (1176 + 1000) = 2176 N
For Participant 2; μ = 1.2, mass = 80 kg, g = 9.8 m/s²
Frictional force = 1.2 * 80 * 9.8 = 940.8N
Total force = (940.8 + 1200) N = 2140.8 N
From the values obtained above, Participant 1 exerts more force than Participant 2, therefore, Participant 1 wins
Modify how could you charge the electric circuit shown below to allow lightbulb a to stay lit even if lightbulb b is removed from its base?
The spectrum of a star shows a set of dark absorption lines equivalent to the absorption lines of the Sun but with one exception: Every line appears at a slightly longer wavelength, shifted toward the red end of the spectrum. What conclusion can be drawn from this observation
Answer:
The shift in the emission spectra of the relative velocity between the star and our planet, is called the relativistic doppler effect
Explanation:
The absorption and emission spectra are measured differently, the emission spectrum is the spectrum emitted by the star and the absorption spectrum is the absorption of these lines by the gases of our atmosphere, this absorption occurs for relatively broad Δλ.
The shift in the emission spectra of the relative velocity between the star and our planet, is called the relativistic doppler effect and has a red shift if the star moves away from us.
[tex]f_o = f_s \sqrt{\frac{1- v/c}{1 + v/c} }[/tex]
Take 47 points. Hurry Someone save me just look the picture
Answer:
suppose buying pizza for a work party leads to positive morale and to the work being done in half the time. Pizza is the independent variable, Work speed is the dependent variable, The mediator, the middle man without which there would be no connection, is positive morale. Denaturation, in biology, the process of modifying the molecular structure of a protein. Denaturation involves the breaking of many of the weak linkages, or bonds (e.g., hydrogen bonds), within a protein molecule that is responsible for the highly ordered structure of the protein in its natural (native) state.
Explanation:
hope this helps have a good rest of your day :) ❤
Explanation:
HW1. For example, suppose buying pizza for a work party leads to positive morale and to the work being done in half the time. Pizza is the independent variable, Work speed is the dependent variable, The mediator, the middle man without which there would be no connection, is positive morale.
HW2. The word denature means to render food unpleasant or dangerous to consume, it is denatured by adding a substance known as a denaturant. Aversive agents—primarily bitterants and pungent agents—are used to produce an unpleasant flavor.
Hope It Helps U
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Which two options are homogeneous mixtures?
A. Sand
B. A wet sponge
C. Liquid dishwashing soap
O D. Vinegar
Answer:
Liquid dishwashing soap
Vinegar
PLEASE HURRY Take 40 points.please just look at the picture.
Answer:
It you get a sushi for work, for a party, then it leads to people being happy, as an independant variable
It is changing the molecular structure of a protein
Explanation:
What type of change happens when the powder inside a firework is burned?
A.Freezing occurs from a chemical change.
B.Light is produced by a chemical change.
C.Rotting occurs from a chemical change.
D.Rust is produced by a chemical change.
Answer:
B light is produced by chemical change
Explanation:
im not the smartest but if you think about it, fireworks make bright lights. And what do they have: powders.
(but I still could wrong, sorry if I am)
A traffic light consists of a horizontal member attached to a vertical support post. The horizontal member extends 7 m to the left of the support post and has a constant mass density of 15 kg/m. Each traffic light has mass of 10 kg, and the street sign has a mass of 4.5 kg. Make sure the connection between the horizontal member and the vertical support post is strong enough to withstand the forces exerted on the horizontal member. Calculate the effects of the forces resulting from the two traffic lights and the street sign on the horizontal member.
Answer:
τ = 539 N m
Explanation:
Let's use the rotational equilibrium relationship, where we set our reference system at the junction of the poles and the counterclockwise rotations we consider positive
τ = Σ τ_i
the mass of the traffic lights is m₁ = 10 kg, the mass of the sign m₂ = 4.5kg and suppose the worst case all the elements connected at the end (x = 7 m)
τ = 2 m₁ x + m₂ x + m₃ x / 2
we calculate the mass of the horizontal pole using the concept of linear density
λ = m₃ / l
m₃ = λ l
we substitute
τ = (2m₁ + m₂) x + λ l x / 2
τ = x (2m₁ + m₂ +λ l / 2)
let's calculate
τ = 7 (2 10 + 4.5 + 15 7/2)
τ = 539 N m
therefore, this is the torque that the joint between the two posts must resist
You drive on Interstate 10 from San Antonio to Houston, half the time at 75 km/h and the other half at 106 km/h. On the way back you travel half the distance at 75 km/h and the other half at 106 km/h. What is your average speed (a) from San Antonio to Houston, (b) from Houston back to San Antonio, and (c) for the entire trip
Answer:
Explanation:
a ) from San Antonio to Houston let distance be d km .
Average speed = total distance / total time
time = distance / speed
Total time = (d / 2 x 75 ) +( d / 2 x 106 )
= .0067 d + .0047 d
= .0114 d
Average speed = d / .0114 d = 87.72 km /h
b ) from Houston back to San Antonio
Total time = (d / 2 x 106 ) +( d / 2 x 75 )
= .0047 d + .0067 d
= .0114 d
Average speed = d / .0114 d = 87.72 km /h
c )
For entire trip :
total distance = 2d
total time = 2 x .0114 d
Average speed = 2 d / 2 x .0114 d
= 87.72 km /h .
Marlon is studying a crab population. He has a large batch of crabs that were captured in the ocean. He places a plastic tag on a leg of each crab and releases the entire batch back into the ocean. The tags
include a phone number that can be called it the crabs are caught. For each crab, Marion records the location he released the crab and the location that it was recaptured. What can Marion measure with
this data
А
the speed the crabs traveled
B
the velocity the crabs traveled
the acceleration of the crabs
D
the displacement of the crabs
Given that the frequency of an EM wave is 4THz, what is its wavelength?
Answer:
The wavelength of the EM wave is 7.5 * 10⁻⁴ m
Explanation:
The velocity of a wave is related to its wavelength by the following formula;
velocity = wavelength * frequency
For an electromagnetic (EM) wave, its velocity is equal to the velocity of light, c = 3.0 * 10⁸ m/s
Given that the frequency and veloity of the given EM wave in the question is known, its wavelength is calculated as follows:
wavelength = velocity/frequency
where velocity of the EM wave = 3.0 * 10⁸ m/s;
frequency = 4THz = 4 * 10¹² Hz
wavelength = 3.0 * 10⁸m/s / 4 * 10¹² Hz
wavelength = 7.5 * 10⁻⁴ m
Therefore, the wavelength of the EM wave is 7.5 * 10⁻⁴ m
Answer:
The wavelength is 7.5 x 10^-5m
You and two of your friends are at the edge of a cliff. Each of you pick up a stone and throw it over the edge at the same time and with the same initial speed. One of you throws the stone at an angle above the horizon, another throws the stone horizontally, and the third throws the stone at an angle below the horizon. Rank the speed of each stone just before it hits the ground from highest to lowest.
Answer:
The speed of stone while hitting the ground in all the three cases will be same .
Explanation:
The speed of stone while hitting the ground in all the three cases will be same .
They all will have same initial kinetic energy because they have same initial speed . Kinetic energy of an object does not depend upon the direction of velocity of the object .
They will all gain kinetic energy due to loss of height .Since they all fall from the same height , gain of kinetic energy in all the three cases will also be same .
Hence final kinetic energy will be same when they hit the ground .
Hence they all have same speed while hitting the ground .
A resistor has a power output of 15 W. If it is powered by 3 AA batteries, what is the current through the circuit?
A torch takes two 1.5 V AA batteries and provides a current of 0.3 A to the bulb. What is the power output of the bulb?
Answer:
well i am sure you need this to so look really hard at this then delete it
Explanation:
1. The speed with which electrons move through a copper wire is typically 10-4 m s-1
.
a. Explain why is it that the electrons cannot travel faster in the conductor?
b. Explain why the electron drift produces heat?
1. a) collisons with the crystal lattice atoms b) collisions with lattice atoms transfers energy.
2. Explain in terms of atomic and electron movement, why resistance increases with temperature.
2. Electrons drift through the lattice, as temperature increases the lattice atoms vibrate more and this increases the probability of
collision and hence resistance to electrons has increased.
3. Calculate the resistance of an aluminum (ρ = 2.8x10-8 Ωm) wire that is 2.0 m long and of circular cross section
with a diameter of 1.5 mm.
3. 32 mΩ
4. Determine the length of tungsten (ρ = 5.6x10-8 Ωm) wire with a diameter of 1.0 mm that is used to make a 20.0 Ω resistor.
4. 280 m
5. A nichrome (ρ = 100x10-8 Ωm) wire has a diameter of 0.40 mm. Calculate the length of this wire needed to carry a current
of 30 mA when there is a potential difference of 12 V across it.
5. 50 m
6. A thin copper (ρ = 1.68x10-8 Ωm, but you don’t need it) wire 200 cm in length has a 9 V dry cell connected between its ends.
Determine the voltage drop that occurs along 30 cm of this wire.
6. 1.35 V
7. If the potential difference across the bulb in a camping lantern is 9.0 V, what is the potential difference across the battery used to
power it?
battery gives the voltage of 9.0 V to the lantern to use it.
8. How much current, in amperes, is in a lightning stroke that lasts 0.05 second and transfers 100 coulombs?
I = q/t = (100 C)/(0.05 s) =2000 A
9. Calculate the resistance of the filament in a light bulb that carries 0.4 A when 3.0 V is impressed across it.
V = IR R = V/I = 7.5 Ω
10. Electric socks, popular in cold weather, have a 90-ohm heating element that is powered by a 9-volt battery.
How much current warms your feet?
V = I/R = 0.1 A
11. Calculate the current of a lightning bolt that delivers a charge of 35 coulombs to the ground in a time of 1/1000 second.
11. I = q/t = 35 000 A.
12. Calculate the current where 10 coulombs of charge pass a point in 5 seconds.
12. I = V/R = 2 A
13. Two light bulbs designed for 120-V use are rated at 40W and 60W. Which light bulb has the greater filament resistance? Why?
13. More current flows in the 60-W bulb, which means the resistance of the filament is less.
P = IV = V2/R, R = V2/P = (120 V)2/(60 W) = 240 Ω; for the 40-W lamp, R = (120 V)2/(40 W) = 360 Ω
14. A battery does 18 joules of work on 3 coulombs of charge. What voltage does it supply?
14. V= E/q= (18 J)/(3 C) = 6V
15. A power line with a resistance of 2 ohms has a current of 80 A in it. The power dissipated in the line is
15. 12800 W.
2
16. A toaster oven is plugged into an outlet that provides a voltage difference of 120 V.
What power does the oven use if the current is 10A?
16. P = IV = 1200 W
17. A VCR that is not playing still uses 10.0 W of power. What is the current if the VCR is plugged into a 120 V electric outlet? 17.
17. P = IV I = P/V = 0.083 A
18. A flashlight bulb uses 2.4 W of power when the current in the bulb is 0.8 A. What is the voltage difference?
18. P = IV V = P/I = 3V
19. A refrigerator operates on average for 10.0 h a day. If the power rating of the refrigerator is 700 W, how much electrical energy
does the refrigerator use in 1 day? (make sure to convert to kW)
19. E = Pt = (0.7 kW)(10.0 h) = 7 kWhours
20. A TV with a power rating of 200 W uses 0.8 kWh in one day. For how many hours was the TV on during this day?
20. E = Pt t = E/P= 0.8 kWh/0.2 kW = 4 h
21. Calculate the voltage difference in a circuit with a resistance of 25 Ω if the current in the circuit is 0.5 A.
21. V = IR = 12.5 V
22. A current of 0.5 A flows in a 60 W light bulb when the voltage difference between the ends of the filament is 120 V.
What is the resistance of the filament?
22. R = V/I = 240 Ω
23. A toy car with a resistance of 20 Ω is connected to a 3 V battery. How much current flows in the car?
23. I = V/R = 0.15 A
24. The current flowing in an appliance connected to a 120 V source is 2 A. How many kilowatt-hours of electrical energy does the
appliance use in 4 h? (2 equations used & convert watts to kW)
24. E = Pt P = IV = 0.24 kW E = 0.96 kWh
25. A calculator uses 9 V battery & draws 0.1 A of current. How much power does it use?
25. P = IV = 0.9 W
26. A battery causes 250 mA to flow when it is applied to a light bulb with a resistance of 50 ohms. How much current would flow if
the same source were applied to a 12 ohm resistor?
26. voltage of the source: V = IR = 12.5 V I = V/R = 1.04 A