Which of the following is the correct formula for kinetic energy (KE)?

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Multiple Choice

Which of the following is the correct formula for kinetic energy (KE)?

Kinetic energy is the energy of motion, and it grows with both how much mass there is and how fast it moves, in a way that depends on the speed squared. That is why the formula has velocity squared: KE = 1/2 m v^2. The 1/2 factor comes from how work required to accelerate an object builds up as velocity increases; doubling the speed makes kinetic energy four times larger. In SI units, mass in kilograms and velocity in meters per second give energy in joules. The version without the 1/2 would overestimate energy by a factor of two. If velocity isn’t squared, you’d end up with momentum units (kg·m/s) rather than energy. And mgh represents potential energy from height in a gravitational field, not kinetic energy. So the correct expression is KE = 1/2 m v^2.

Kinetic energy is the energy of motion, and it grows with both how much mass there is and how fast it moves, in a way that depends on the speed squared. That is why the formula has velocity squared: KE = 1/2 m v^2. The 1/2 factor comes from how work required to accelerate an object builds up as velocity increases; doubling the speed makes kinetic energy four times larger. In SI units, mass in kilograms and velocity in meters per second give energy in joules. The version without the 1/2 would overestimate energy by a factor of two. If velocity isn’t squared, you’d end up with momentum units (kg·m/s) rather than energy. And mgh represents potential energy from height in a gravitational field, not kinetic energy. So the correct expression is KE = 1/2 m v^2.

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