Kinetic Energy Calculator
Find the energy of a moving object, or the mass or speed that gives a certain kinetic energy.
How to use the Kinetic Energy Calculator
- Choose the solve for.
- Enter the mass and pick its unit.
- Enter the velocity and pick its unit.
- Enter the kinetic energy and pick its unit.
- Press Calculate. The result updates automatically as you type, and you can switch the result unit at any time.
About the Kinetic Energy Calculator
Kinetic energy is the energy an object has because it is moving. Because velocity is squared, speed matters far more than mass: doubling speed quadruples the energy. That is why a crash at 60 mph is so much more destructive than one at 30 mph, and why stopping distances grow so quickly with speed, since brakes must turn all of that energy into heat.
The same formula is used to compare bullet muzzle energy (often quoted in foot-pounds), to estimate the energy a regenerative braking system could recover, and in physics problems about collisions and conservation of energy. The classical formula is accurate for everyday speeds; only near the speed of light does relativity require a different expression.
Formula
KE = ½ × m × v²
m = 2 × KE ÷ v² v = √(2 × KE ÷ m)
With mass in kilograms and velocity in m/s, energy is in joules. Example: a 1,500 kg car at 60 mph (26.82 m/s) has ½ × 1,500 × 26.82² ≈ 539,600 J, or about 540 kJ.
Example calculation
Using the default values:
- Solve for = Kinetic energy
- Mass = 1500 kg
- Velocity = 60 mph
the calculator returns:
- Kinetic energy: 539.5809 kJ
- Momentum: 40,233.6 kg·m/s
Frequently asked questions
What happens to kinetic energy if speed doubles?
It becomes four times larger, because kinetic energy depends on velocity squared.
What is the kinetic energy of a 2 kg ball at 3 m/s?
½ × 2 × 3² = 9 J.
How do I convert joules to foot-pounds?
Divide joules by 1.3558. 1,000 J ≈ 737.6 ft·lb.
Last updated: · Category: Science calculators