Table of Contents
- Vehicle example
- Bullet example
- Kinetic energies for various objects
Kinetic energy is the energy possessed by a body, object or particle due to its motion. In other words, any object, body or particle with a mass and speed has kinetic energy. An object, body or particle with zero speed (which means that it’s stationary) will have zero kinetic energy.
Even if it has low mass, a bullet fired from a gun has a relatively high kinetic energy due to the fact that it’s travelling at very high speed.
To calculate kinetic energy multiply the mass of the body (object) with the square value of the speed and divide the result to two. The formula (equation) to calculate kinetic energy is :
- Ek [J] – kinetic energy
- m [kg] – mass
- v [m/s] – speed
The unit of measurement of kinetic energy is joule [J].
Calculate the kinetic energy of a vehicle of mass 1200 kg, travelling at a speed of 125 kph.
Step 1. Convert the vehicle speed from [kph] to [m/s], by dividing the [kph] value to 3.6:
Step 2. Calculate the kinetic energy Ek [J] of the vehicle using equation (1):
Calculate the kinetic energy of a bullet of mass 30 g, travelling at a speed of 2600 feet per second.
Step 1. Convert the bullet’s mass from [g] to [kg], by dividing the [g] to 1000:
Step 2. Convert the bullet’s speed from [ft/s] to [m/s], by dividing the [ft/s] value with 3.281:
Step 3. Calculate the kinetic energy Ek [J] of the bullet using equation (1):
The kinetic energy calculator allows you to calculate the kinetic energy of a body (object) with a given mass and travelling speed. You need to enter the mass and speed parameters and choose the desired unit of measurement.
The default unit of measurement for energy is Joule. If you want the result displayed in another unit, use the dropt down list to choose and click the CALCULATE button again.
Kinetic energies for various objects
|Object||Mass [kg]||Speed [m/s]||Kinetic energy [J]|
|Earth orbiting the Sun||5.98·1024||2.98·104||2.65·1033|
|Moon orbiting the Earth||7.35·1022||1.02·103||3.82·1023|
|Rocket moving at escape speeda||500||1.12·104||3.14·1010|
|Automobile at 55 miles per hour||2000||25||6.3·105|
|Stone dropped from 10 m||1||14||98|
|Golf ball at terminal speed||0.046||44||45|
|Raindrop at terminal speed||3.5·10-5||9||1.4·10-3|
|Oxygen molecule in air||5.3·10-26||500||6.6·10-21|
a escape speed is the minimum speed an object must attain near the Earth’s surface if it is to escape the Earth’s gravitational force.
 David Halliday, Robert Resnick, Jearl Walker, Fundamentals of Physics, 7th edition, John Wiley & Sons, 2004.
 Benjamin Crowell, Light and Matter – Physics, 2007.
 Raymond A. Serway and John W. Jr. Jewett, Physics for Scientists and Engineers, 6th edition, Brooks/Cole Publishing Co.,2004
 Jiansong Li, Jiyun Zhao, and Xiaochun Zhang, A Novel Energy Recovery System Integrating Flywheel and Flow Regeneration for a Hydraulic Excavator Boom System, Energies 2020.
 Leo H. Holthuijsen, Waves in oceanic and coastal waters, Cambridge University Press, 2007.
 Kira Grogg, Harvesting the Wind: The Physics of Wind Turbines, Carleton College, 2005.