AP Physics 1 · Unit 3 · Energy

Conservative and Non-conservative Forces Practice Problems

Compare work along different routes and choose a reference for potential energy. Practice gravity on ramps, friction along detours, closed routes, and mechanical energy transferred to thermal energy.

12 questions6 conceptual · 6 calculation

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Simulation scene from the Conservative and Non-conservative Forces lesson. — A scene from the related lesson. Open the practice to work through the questions.

What you’ll practice

Find out whether the route changes the work

Compare paths with shared endpoints

Calculate gravity’s work for different ramps and compare friction on a direct route and a detour. Interpret a complete return route.

Choose a potential-energy reference

Calculate gravitational potential energy from a chosen zero and show how a reference shift affects values without changing the physical energy difference.

Track mechanical-energy changes

Connect gravity’s work with potential energy and account for friction on a rough ramp. Distinguish a fixed force vector from a pull that follows the direction of travel.

A question from this set

Two ramps with the same height change

Identical crates descend two frictionless ramps from the same starting height to the same finishing height. One ramp is long and shallow; the other is shorter and steeper. How does the work done by gravity compare?

Gravity does more work on the longer ramp because the crate travels farther.
Gravity does the same work because the vertical height change is the same.
Gravity does more work on the steeper ramp because the downhill force is larger.

Try it in the practice set

The two smooth ramps connect the same starting and finishing heights.

Key ideas

Conservative work depends on the endpoints

Gravity’s work is tied to height change

Near Earth, Wgravity = −ΔUg. For fixed endpoints, a longer route does not by itself change gravitational work. A closed route returns to the same gravitational potential energy.

Friction depends on the contact route

Sliding friction removes mechanical energy over the traveled path. A detour can increase this transfer even when initial and final heights remain the same.

See the physics

Switch routes and energy references

After checking an answer, compare the prepared ramps or detours. Inspect gravity work, friction work, and potential-energy changes while keeping track of the shared endpoints.

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 conservative and non-conservative forces?

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

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