Kinetic Energy
Energy of a moving object.
Formula
Live Calculator
MembersVariables
Example
A 2 kg ball at 3 m/s: KE = ½·2·3² = 9 J.
How it works
This formula tells you how much energy an object has because it is moving. It depends on mass and on the square of speed, so doubling the speed makes the kinetic energy four times larger, which is why fast-moving objects can do much more work or cause more damage. The bd factor comes from how the work done to speed up an object builds up as its velocity increases from zero.
When to use it
Use this when you need the energy of a moving object, such as a rolling cart, a thrown ball, a car, or any object in motion. It is also used in impact, stopping-distance, and energy-conversion problems.
Worked example, step by step
A 4 kg skateboard is moving at 5 m/s. KE = 1/2 d7 m d7 v^2 KE = 1/2 d7 4 d7 5^2 KE = 2 d7 25 KE = 50 J
Common mistakes to avoid
- Using speed in km/h instead of converting to m/s
- Forgetting to square the velocity
- Leaving out the unit joules (J) in the final answer
Did You Know?
Because kinetic energy depends on speed squared, doubling your car's speed quadruples the energy in a crash.
Share this formula
More in Physics
View allNewton's Second Law
BasicForce equals mass times acceleration.
Gravitational Potential Energy
BasicEnergy stored due to height in a gravitational field.
Work Done
BasicWork done by a force over a distance.
Power
BasicRate of doing work.
Momentum
BasicQuantity of motion of an object.
Impulse
IntermediateChange in momentum from a force over time.