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AP Physics 1 · Unit 3 · Energy

Conservation of Energy Practice Problems

Use mechanical energy to find speeds and heights on drops, ramps, curved tracks, swings, and projectile flights. Compare ideal motion with a swing that loses mechanical energy.

12 questions6 conceptual · 6 calculation

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

What you’ll practice

Follow kinetic and gravitational energy together

Compare paths through the same height change

Predict final speed for free fall, straight ramps, and curved tracks under the stated ideal conditions. Distinguish a speed comparison from an arrival-time comparison.

Calculate energy at selected positions

Use initial motion and changes in height to find a speed or height. Retain horizontal kinetic energy at the peak of an angled projectile.

Account for a measured loss

Compare an ideal swing with a resisted swing and use the mechanical-energy difference to quantify the loss.

A question from this set

Three paths to a lower height

Three identical sliders start from rest and descend through the same vertical height: one in free fall, one on a frictionless straight ramp, and one on a frictionless curved track. Ignore air resistance and rotation. How do their speeds compare at the lower height?

  • The freely falling slider must have the greatest final speed.
  • All three have the same final speed.
  • The curved-track slider must have the greatest final speed because it travels farther.
Try it in the practice set
Three paths to a lower heightThree identical sliders start from rest and descend through the same vertical height: one in free fall, one on a frictionless straight ramp, and one on a frictionless curved track. Ignore air resistance and rotation. How do their speeds compare at the lower height?DropStraightCurvedSame height change
Three ideal paths descend through the same vertical height.

Key ideas

State when mechanical energy is conserved

Use K + Ug for the chosen system

For these ideal gravity-driven motions, kinetic plus gravitational potential energy stays constant. A decrease in Ug can become an increase in K.

A path can change timing without changing final speed

Equal vertical drops from identical initial conditions give equal final speeds when no mechanical energy is lost. That result does not require identical travel times.

See the physics

Compare paths, peaks, and energy records

Check your result, then switch between the prepared drop, straight-ramp, and curved-track trials. Inspect the speed at a marker or compare an ideal swing’s energy with a resisted swing.

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?

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

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