Work and Energy Test

A horse pulls on an object with a force of 300 newtons and does 12,000 joules of work. How far was the object moved?

40 m

If a pulley system with an actual mechanical advantage of 2,000,000 is used in lifting a 2,000 lb. car, what effort would be needed to move the car?

.001 lb

If a pulley system with an ideal mechanical advantage of 2 is used in lifting a 2,000 lb. car, how far would the car move if the effort moved 2 ft.?

1 ft

If a pulley system with an ideal mechanical advantage of 2,000,000 is used in lifting a 2,000 lb. car, how far would the car move if the effort moved 2 ft.?

1*10^-6 ft

If a net force of 25 N is exerted over a distance of 4 m to the right on a 2 kg mass initially at rest and moves it, what is the final velocity of the object?

10 m/s

As a pendulum swings back and forth, its total energy is 16 J. What is its potential energy at 3/4 its maximum height?

12 J

Given that a lever has a mechanical advantage of 6.0 and is 100% efficient, if the resistance is to be lifted 2.0 inches, then how far must the effort move

12 in.

If a car engine burns an equivalent of 20,000 joules of energy and attains a kinetic energy of 5,000 J, how much energy is dissipated in the form of heat?

15,000 J

A car traveling at 60 mph has how much more energy than a car going at 15 mph? KE increases by a factor of _____.

16

If an engine operates on an input temperature of 80 0 K and an exhaust temperature of 60 0 K, calculate the efficiency of the engine.

25%

How many times does the kinetic energy of a car increase when traveling 60 mph as opposed to traveling 30 mph? K.E. increases _____ times.

4

As a pendulum swings back and forth, its total energy is 16 J. What is its kinetic energy at 3/4 its maximum height?

4 J

Calculate the kinetic energy in joules of a 10g bullet moving at 300m/s.

450 J

Calculate the mechanical advantage of a pulley system if only 10 lb is required to lift a 500 lb block.

50

A 50 g mass of metal (c = 0.20 cal/g°C) at 90°C is dropped into water at 30°C and the temperatures stabilize at 40°C. Calculate the mass of water used.

50 g

Calculate the kinetic energy of a 4.00 kg object traveling at 16.0 m/s.

512 J

A man with a mass of 60 kg walks up two flights of stairs in going from the first floor to the third floor (10 meters). Calculate his increase in potential energy.

5900 J

Calculate the increase in potential energy of a 60.0-kg man who climbs a ladder 10.0 meters high.

5900 J

A force of 80 N is exerted on an object on a frictionless surface for a distance of 4 meters. If the object has a mass of 10 kg, calculate its velocity. v = _____ m/s

8

Starting from rest, a 5.00 kg steel sphere rolls down a frictionless ramp with a height of 4.00 m. What is the sphere's speed when it reaches the bottom of the ramp? (Use 9.80 for the value of "g.")

8.85 m/s

A car traveling at 60 mph has how much more energy than a car going at 20 mph? KE increases by a factor of _____.

9

If the speed of an object were to triple, what would be the increase of kinetic energy? KE1=___KE2

9

force: A. push or pull B. energy rating with respect to time C. ability to do work

A. push or pull

power: A. push or pull B. energy rating with respect to time C. ability to do work

B. energy rating with respect to time

Is the expression "The bigger they are, the harder they fall" a generally true statement since, in the absence of air resistance, all objects fall with the same acceleration due to gravity? Pick the most correct answer. A. Yes, because as a heavier man falls, he comes closer to the center of the earth and he falls faster. B. No, since the acceleration is the same, each man will be affected the same by it as he falls. C. Yes, since F = ma, therefore "a" will be the same in each case, but the mass of each will be different. D. Yes, since F = ma, the heavier an object is, the more it will accelerate and therefore fall with more force.

C

energy: A. push or pull B. energy rating with respect to time C. ability to do work

C. ability to do work

True or False: The latent heat of fusion of aluminum is 93 kcal/kg at 660°C. The amount of energy needed to melt 10 0 kg of aluminum at the melting point is approximately 75,000 kcal

False

With a pulley system, a force of only 50 lb can lift a 500-lb weight. What is the mechanical advantage if this system is 100% efficient?

MA = 10

True or False: Examples of energy transfers include collisions in chemical and nuclear reactions.

True

True or False: The earth can be considered a heat engine because it receives heat from the sun and converts it into mechanical energy to produce winds and evaporate water.

True

True or False: The total energy of the universe remains constant.

True

Three mountain climbers set out to climb a mountain from the same altitude and all arrive at the same location at the top. Mountain climber A took a long gradual slope to the top, B went a steeper but shorter path, and C tackled the sheer straight side to the top. Assume all three climbers weigh the same. Which did the most work?

all did the same amount of work

Three mountain climbers set out to climb a mountain from the same altitude and all arrive at the same location at the top. Mountain climber A took a long gradual slope to the top, B went a steeper but shorter path, and C tackled the sheer straight side to the top. Assume all three climbers have the same mass. Which climber gained the greatest potential energy?

all gained the same amount of PE

The __________ Law of Thermodynamics states that whenever energy is transformed from one form to another, some energy is transformed into heat energy and is unusable.

second