AP Physics 1 · Unit 3 · Energy

Conservation of Energy with Work Practice Problems

Extend energy calculations to motors, resistance, and springs. Compare smooth and rough routes, then solve stopping tracks, connected ramps, and powered uphill motion.

12 questions6 conceptual · 6 calculation

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Simulation scene from the Conservation of Energy with Work lesson. — A scene from the related lesson. Open the practice to work through the questions.

What you’ll practice

Include the energy transferred during the motion

Choose an energy system

Decide which objects and energy stores to include. Account for gravity, a spring, and work by forces outside the chosen system without counting an interaction twice.

Calculate work and final motion

Use motor or resistance work with kinetic, gravitational, and elastic-energy changes. Find stopping distance, final speed, or required motor work.

Compare smooth and rough routes

Analyze slides with the same drop but different friction transfers. Extend the accounting to a spring guide and a connected incline system.

A question from this set

A motor pulls at steady speed

A motor pulls a cart at constant speed along a level rough track. The motor does positive work. Must the cart–Earth system’s mechanical energy increase?

Yes, positive motor work always increases mechanical energy.
No, negative friction work can cancel the positive motor work.
No, gravity does negative work on the level track.

Try it in the practice set

The motor supplies work while the cart travels at constant speed on a rough track.

Key ideas

Energy accounting follows the system boundary

External work can change mechanical energy

For a system whose mechanical stores are K, Ug, and Us, work by the other included external forces equals the change in their sum. A motor can add mechanical energy while resistance removes it.

Use gravity consistently

Include the gravitational potential-energy change when Earth is part of the system. Avoid also treating the same gravitational interaction as an additional work input in that equation.

See the physics

Compare the work inputs with the recorded energy change

After checking each answer part, run a smooth or rough slide, a spring launch, or a motor-driven cart. Compare motor and resistance work with kinetic and potential-energy records.

Use a hint for a starting point or open a worked solution to follow the reasoning. Your progress saves in this browser, so you can return to unfinished questions.

Ready for conservation of energy with work?

Begin with a conceptual question, then work through the calculations.

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