U4: Test Review-Energy

​U4: Test Review -Energy

By Maria Cerca

In order for work to be done, the displacement must be parallel to the force applied.

Work

​Power is calculated by dividing work by time.
Inversely Proportional: Power, Time
Directly Proportional: Power, Work

Power

Drag and Drop

​ ​

Placeholder

is the unit for energy. ​

Placeholder

is the unit for power.

Drag these tiles and drop them in the correct blank above

Newton

Coulomb

Joule

Watt

Meter

Multiple Choice

In order to maximize power, which of the following could be done?

• decrease the time in which you did work

• increase the amount of work

• increase the force

• all of the above

Categorize

Options (11)

• A weightlifter lifting a barbell upwards

• A book falling to the ground, where gravity does work on it

• A person pushing a box across a room, causing it to move

• A construction worker lifting heavy materials

• A person holding a heavy object, but the object does not move

• Pushing against a stationary wall

• Carrying a box across a room horizontally at a constant speed

• Holding a heavy bag while standing still 

• A person sitting on a chair while holding a book

• A car parked on a hill without moving

• A person waiting for a bus while holding a suitcase

Classify the following as examples of work or non-examples of work.

Work

No work

Multiple Choice

A steady force of 20 N is applied to push a cart that moves parallel to the direction of the force. If 75 J of work is done, how far does the cart move?

• 1500 m

• 3.75 m

• 14,700 m

• 3.75 W

Multiple Choice

It takes 5 seconds for Taylor to do 200 J of work. What is her power output?

• 1,000 W

• 0.025 W

• 40 W

• 100 W

Multiple Choice

What is work in the context of physics?

• velocity over time

• a type of force

• what you gotta do to get paid $$$

• change in energy

Multiple Choice

Which is the best example that something has kinetic energy?

• a car parked on a steep hill

• a tennis ball rolling across the court

• a picture hanging on the wall

• a piece of coal before it's burned

Multiple Choice

When the force is perpendicular to the motion, the work being done is 0.

• True

• False

Multiple Choice

How much time is needed to produce 720 Joules of work if 90 watts of power is used? 

• 0.125 s

• 8 s

• 64800 s

• 80 s

Multiple Choice

If you have the same work as someone, but in less time

• You are more powerful

• You are less powerful

• You have the same power

Multiple Choice

Two people are lifting the same weight as shown in the animation. If they both do 10 reps, who will supply the most power?

• Bro A

• Bro B

• They both will do the same work

• Can't tell without knowing the weight they are lifting

Multiple Choice

Two people are lifting the same weight as shown in the animation. If they both do 10 reps, who will do the most work?

• Bro A

• Bro B

• They both will do the same work

• Can't tell without knowing the weight they are lifting

Multiple Choice

A construction worker uses a pulley and a rope to raise an 85 kg with an acceleration of 9.8 m/s² person to a height of 2 m in 6 s. How much power is he supplying?

• 1,670 W

• 833 W

• 278 W

• 417 W

Multiple Choice

This weight lifter raised 105 kg with an acceleration of 9.8 m/s² to a height of approximately 2.31 m in 9 seconds. How much power did he developed?

• 264 Watts

• 1029 Watts

• 2,377 Watts

• 4,009 Watts

Multiple Choice

If he weighs 700 N and climbs at a constant speed to the top of an 8 m vertical rope in 10 s. The average power expended by him to overcome gravity is most nearly

• 1.1 Watts

• 87.5 Watts

• 560 Watts

• 875 Watts

• 5,600 Watts

​Mechanical Energy = Total Energy

​Mechanical Energy = Total Energy
ME = PE + KE

​Potential Energy	​Kinetic Energy
​Definition: Stored Energy	​Definition: Energy of Motion
​Ex. Chemical, Gravitational, Elastic	​Ex. Electrical, Thermal, Radiant, Sound
​	​

​Gravitational Potential Energy

Def: Energy due to the height of the object.

​Kinetic Energy

Def: Energy due to the motion of the object.

Law of Conservation of Energy

Energy is not lost. It is converted from one type to another.

Multiple Choice

A hawk is flying 50 meters above the ground. Its mass is 10 kg. What is its potential energy?

• 490 N

• 4900 J

• 3.34 x 10^-8 J

• 250 J

Multiple Choice

A hawk is flying at 5 m/s and its mass is 10 kg. What is its kinetic energy?

• 250 N

• 250 J

• 125 N

• 125 J

Multiple Choice

A 3 kg drone is hovering 100 m above the ground. If its potential energy is equal to its kinetic energy, what is the velocity?

• 2940 J

• 30,000 m/s

• 15,000 m/s

• 44.3 m/s

Multiple Choice

A 10 kg hawk is flying at 15 m/s. If its potential energy is equal to its kinetic energy, what is the height?

• 11.5 meters

• 2250 meters

• 1125 J

• 1470 meters

Multiple Choice

If the Law of Conservation of Energy is true, which type of energy will stay constant?

• kinetic

• potential

• elastic

• mechanical/total

Multiple Choice

If the velocity of a moving object doubles, what will be the resulting change in its Kinetic Energy?

• KE also doubles

• KE stays the same

• KE halves

• KE quadruples

Multiple Choice

If a rock falls off of a cliff, what will happen to kinetic energy as the rock falls?

• KE stays the same

• KE increases

• KE decreases

Multiple Choice

Which point has greatest potential energy?

• A
• B
• C
• none

Multiple Choice

Which point has greatest kinetic energy?

• A
• B
• C
• none

Multiple Choice

If a rock falls off of a cliff, what will happen to potential energy as the rock falls?

• GPE stays the same

• GPE increases

• GPE decreases

Multiple Choice

If a rock falls off of a cliff, what will happen to total mechanical energy as the rock falls?

• ME stays the same

• ME increases

• ME decreases

Multiple Choice

In the picture below, a boulder of mass 150 kg rolls down an incline 15m tall. What is the speed of

the boulder at the bottom of the incline?

• 51.4 m/s

• 17.1 m/s

• 8.57 m/s

• 34.3 m/s

Multiple Choice

A 2 kg stone is thrown directly upwards with a velocity of 10 m/s. What is the maximum height that the stone will reach if it starts at a height of 0 meters?

(Hint: Law of Conservation of Energy.)

• 5.1 m

• 10.2 m

• 9.8 m

• 20 m