What is the equation for kinetic energy?

What is the equation for kinetic energy?

• A. Kinetic energy = mass x velocity
• B. Kinetic energy = 0.5 x mass x (velocity)^2
• C. Kinetic energy = mass x velocity^2
• D. Kinetic energy = mass x height

Answer: (B)

Kinetic energy is the energy an object has because it is moving. The amount depends on both how heavy the object is and how fast it’s moving, and the correct formula is KE = 1/2 m v^2. The squared velocity means speed has a big effect: doubling the speed makes the kinetic energy go up by a factor of four. The factor of 1/2 matters because it mirrors how work is required to accelerate a mass from rest. Units come out in joules (kg·m^2/s^2). The other expressions don’t describe kinetic energy: mass times velocity is momentum, mass times velocity squared would give an incorrect amount of energy (missing the 1/2 factor), and mass times height relates to gravitational potential energy, not kinetic energy.

Kinetic energy is the energy an object has because it is moving. The amount depends on both how heavy the object is and how fast it’s moving, and the correct formula is KE = 1/2 m v^2. The squared velocity means speed has a big effect: doubling the speed makes the kinetic energy go up by a factor of four. The factor of 1/2 matters because it mirrors how work is required to accelerate a mass from rest.

Units come out in joules (kg·m^2/s^2). The other expressions don’t describe kinetic energy: mass times velocity is momentum, mass times velocity squared would give an incorrect amount of energy (missing the 1/2 factor), and mass times height relates to gravitational potential energy, not kinetic energy.