Physics U5 Work & Energy Test Review

Energy & Work Test Review

​Physics: Unit 5

Objectives

• Calculate work, kinetic energy, potential energy, and mechanical energy using appropriate formulas. (HS-PS3-1, HS-PS3-2)

• Apply the law of conservation of energy to analyze motion in systems such as roller coasters, pendulums, and machines. (HS-PS3-1, HS-PS3-3)

• Evaluate the efficiency of machines and explain why efficiencies greater than 100% are not physically possible. (HS-PS3-3)

Poll

How confident do you feel about mastering the objectives of this unit?

• 🔴 Not confident yet – I need more practice with the concepts.

• 🟠 Somewhat confident

  – I can do some calculations but still make mistakes.

• 🟡 Mostly confident

  – I understand the formulas and can usually solve problems.

• 🟢 Very confident

  – I can explain and calculate energy/work problems without help.

15 Questions

Formula sheet and calculator provided

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​U5: Work & Energy Test

W = F × d

​Work

Multiple Choice

Consider the two examples below. In which instance is more work done? 

• Example A 
• Example B 
• Example A and Example B represent the same amount of work. 
• Neither example represents any work done. 

Multiple Choice

A student pushes a 15 kg box with a force of 50 N across the floor for a distance of 4 m. The box moves at a constant speed.

How much work does the student do, and why does this work not increase the box’s kinetic energy?

• 200 J; because the work is used to overcome friction rather than change kinetic energy.

• 200 J; because all of the work is stored as potential energy.

• 600 J; because the box has a mass of 15 kg and the force is applied.

• 50 J; because the box is moving at a constant speed and no work is done.

• Formula: v = √(2gh)

• At the bottom of a hill, potential energy (mgh) becomes kinetic (½mv²).

​

Conservation of Energy

Draw

A skateboarder of mass 60 kg starts from rest at the top of a 20 m ramp. Ignoring friction and air resistance, what is the skateboarder’s velocity at the bottom of the ramp?

Multiple Choice

Two roller coasters, A and B, both start at a height of 40 m. Coaster A is smooth with no friction, while Coaster B loses 25% of its mechanical energy to friction by the time it reaches the bottom.

Which statement best describes their velocities and the role of friction?

• Both coasters reach the same velocity of 28.0 m/s because mass cancels out in the equation.

• Coaster A reaches about 28.0 m/s, while Coaster B is slower at about 24.3 m/s, because some of its energy is transformed into heat due to friction.

• Coaster A and Coaster B both stop at the bottom because friction cancels all energy.

• Coaster A is faster because it has less mass than Coaster B.

PE = mass x gravity x height

​

​Gravitational Potential Energy

Multiple Choice

A 0.60 kg snowball is dropped from a 4.0 m roof. Ignoring air resistance, what is its gravitational potential energy before release?

• 12 J

• 19 J

• 24 J

• 30 J

ME = KE + PE

KE = ½ m v²
PE = m g h

Mechanical Energy

Drag and Drop

A 1,200 kg car is driving up a hill at a speed of 15 m/s. The hill is 10 m tall. What is the car’s total mechanical energy at that point?​

Placeholder

Drag these tiles and drop them in the correct blank above

135,000J

270,000J

112,000J

252,720J

• Find the height change: h = L – (L cos θ)

• Use energy conservation:

  v = √(2gh)

​

​Pendulum Velocity

Open Ended

A 3.5 m pendulum is released from 40°. What is its velocity at the lowest point?

• Formula: Efficiency = (W_out ÷ W_in) × 100

• No machine is 100% efficient

• Some input energy is always lost as heat, sound, or friction

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​Machine Efficiency

Math Response

A machine takes in 800 J of input work and outputs 500 J. What is its efficiency?

Type answer here

Correct Answer: 500\div800\times100=62.5

Deg^°

Rad

Multiple Choice

A student carries their heavy backpack (15 kg) straight up three flights of stairs, while another student uses the same amount of energy to slowly walk the same backpack up a long ramp to the same height. The student who used the ramp did less work because the ramp made the climb easier.

• True
• False

Poll

How confident are you in your ability to perform well on the U5: Work & Energy test?

• 🔴 Not ready – I still need a lot more practice.

• 🟠 Getting there – I understand some parts but still get confused.

• 🟡 Almost ready – I can solve most problems but need to review a little more.

• 🟢 Test ready! – I feel confident and prepared.