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?
A. 2.2 × 102 joules
B. 4.7 × 102 joules
C. 5.2 × 102 joules
D. 5.8 × 103 joules

Answer 1

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