Kinetic Energy Examples in Physics

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Kinetic Energy.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Physics.

Concept Recap

The energy an object possesses by virtue of its motion, depending on both mass and velocity.

The faster something moves and the heavier it is, the more kinetic energy it has.

Read the full concept explanation →

How to Use These Examples

  • Read the first worked example with the solution open so the structure is clear.
  • Try the practice problems before revealing each solution.
  • Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: Kinetic energy depends on velocity squared -- double the speed, quadruple the energy.

Common stuck point: KE is always positive (velocity is squared), regardless of direction.

Worked Examples

Example 1

easy
What is the kinetic energy of a 3 \text{ kg} ball moving at 8 \text{ m/s}?

Solution

  1. 1
    Use the kinetic energy formula: KE = \frac{1}{2}mv^2.
  2. 2
    Square the speed first: 8^2 = 64.
  3. 3
    KE = \frac{1}{2}(3)(64) = 96 \text{ J}

Answer

KE = 96 \text{ J}
Kinetic energy is the energy of motion. It depends on both mass and velocity, but velocity has a squared relationship, so doubling speed quadruples KE.

Example 2

medium
A car doubles its speed from 15 \text{ m/s} to 30 \text{ m/s}. By what factor does its kinetic energy change?

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

medium
A 0.5 \text{ kg} ball has 100 \text{ J} of kinetic energy. What is its speed?

Example 2

easy
A 1200 \text{ kg} car doubles its speed from 15 \text{ m/s} to 30 \text{ m/s}. By what factor does its kinetic energy increase?
← Back to Kinetic Energy Formula Explained Practice Mode

Background Knowledge

These ideas may be useful before you work through the harder examples.

energyvelocitymass