Question

A car has a kinetic energy of 1.9 * 103 joules. If the velocity of the car is decreased by half, what is its kinetic energy?

Answer 1

Kinetic Energy = 1.9 * 10³

If velocity is decreased by half, kinetic energy will decrease by 4 times, so it would be: 1.9 * 10³ /4 = 0.475 * 10³ OR 475 Joules

So, your answer is 475 J

Answer 2

Kinetic energy is calculated by one half of the product of mass and velocity squared or expressed as:

KE = 1/2 (mv²)

We calculate as follows:

KE1 = 1/2 (mv²) = 1.9 * 10^3 joules
KE2 = 1/2 (m(v/2)²) = 1/2 (mv²/4)
KE2 = 1.9 * 10^3 joules / 4 = 475 J