Kinetic Energy Calculator
Enter any two of mass, velocity and kinetic energy and this calculator solves for the third using KE = 1/2 m v^2, with mass in kilograms, velocity in m/s and energy in joules.
How to calculate kinetic energy
- Choose whether to solve for energy, velocity or mass.
- Enter the two known values in SI units.
- Read the result in joules, metres per second or kilograms.
Examples
Energy from mass and velocity
m = 2 kg, v = 3 m/s
KE = 9 J
Velocity from mass and energy
m = 2 kg, KE = 9 J
v = 3 m/s
Frequently asked questions
What is the kinetic energy formula?
Kinetic energy is one half times mass times velocity squared: KE = 1/2 m v^2. Energy is in joules when mass is in kg and velocity in m/s.
How do I find velocity from kinetic energy?
Rearrange to v = sqrt(2 x KE / m). The result is the speed magnitude, which is always zero or positive.
How do I find mass from kinetic energy?
Rearrange to m = 2 x KE / v^2. Velocity must not be zero, otherwise the mass is undefined.
Why is energy the same for negative velocity?
Kinetic energy depends on velocity squared, so a speed of -3 m/s and +3 m/s give the same energy. Direction does not matter for KE.
Can kinetic energy be negative?
No. Because it uses velocity squared and positive mass, kinetic energy is always zero or positive, so negative energy inputs are rejected.
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