An object has a mass of 6 kg. The object's kinetic energy uniformly changes from 54 KJ to 150 KJ over t in [0, 8 s]. What is the average speed of the object?

1 Answer
May 30, 2016

sqrt(2)

Explanation:

Kinetic energy is given by the equation KE=1/2mv^2 where m is the mass and v is the velocity (speed)

The starting condition is 54 = 1/2*6v_s^2
:.v_s^2=18

v_s= 3sqrt(2)

The end condition is 150 = 1/2*6v_e^2

v_e^2 = 50

v_e= 5sqrt(2)

The average speed is (v_e-v_s)/2

(5sqrt(2)-3sqrt(2))/2 = (2sqrt(2))/2 = sqrt(2) k/s