Energy · 02 / 05
Kinetic Energy
Kinetic energy measures the energy associated with motion. Mass matters once; speed matters twice because the speed is squared.
The learner question
Why does speed matter so much more than mass?
Doubling the mass doubles kinetic energy. Doubling the speed quadruples it. That asymmetry is the main idea to notice.
Core relationship
Kinetic energy is scalar. Direction does not change its value; speed does.
Motion-energy lab
mass
2.0 kg
speed
4.0 m/s
kinetic energy
16.0 J
Mass2.0 kg
Speed4.0 m/s
Double the mass
16.0 J32.0 J
2× kinetic energy
Double the speed
16.0 J64.0 J
4× kinetic energy
Connection to work
The net work done on an object equals its change in kinetic energy. Work is the transfer process; kinetic energy is the motion store that changes.
Transfer check