Question

A 20 kg mass with an initial velocity of 10 m/s slides to a stop in 2 meters. What is the net work down on the mass? a.) 250 J b.) 500 J c.) 120 J d.) 20 J e.) None of the above

Answer 1

12500 J

Step-by-step explanation:

m = 20 kg, u = 10 m/s, s = 2 m, v = 0

Use third equation of motion

v^2 = u^2 = 2 a s

0 = 100 - 2 a x 2

100 / 4 = - a

a = - 25 m/s^2

Force, F = m a = 20 x 25 = 500 N

Work done = F x s = 500 x 25 = 12500 J