Kinetic Energy Calculator
Free kinetic and potential energy calculator — KE = ½mv² and PE = mgh in joules, with an animated energy illustration.
Everyday Uses
Physics homework
Solve KE = ½mv² and PE = mgh in joules, with the working shown and an animated ramp.
Road safety
See why stopping distance grows so fast — kinetic energy quadruples when speed doubles.
Rollercoasters
Track how potential energy at the top of a hill becomes kinetic energy at the bottom.
Engineering
Size flywheels, hammers, and impacts by the energy a moving mass carries.
Frequently Asked Questions
What is the formula for kinetic energy?
Kinetic energy is KE = ½ × m × v², where m is mass in kilograms and v is speed in metres per second; the result is in joules (J). For example, a 2 kg object moving at 10 m/s has KE = ½ × 2 × 10² = 100 J. Because speed is squared, doubling the speed multiplies the kinetic energy by four.
What is the difference between kinetic and potential energy?
Kinetic energy is the energy of motion (KE = ½mv²); gravitational potential energy is stored by height (PE = m·g·h, with g = 9.81 m/s²). As an object falls, potential energy converts into kinetic energy while the total mechanical energy stays constant (ignoring air resistance). At the bottom of a drop, PE at the top equals KE at the bottom.
How do you find velocity from kinetic energy?
Rearrange KE = ½mv² to v = √(2·KE ÷ m). For 100 J of kinetic energy carried by a 2 kg mass, v = √(2 × 100 ÷ 2) = √100 = 10 m/s. The same rearrangement gives the impact speed when all of an object's potential energy becomes kinetic: v = √(2gh).