Help me with this Physic problem, please.?

Question

A 1500 kg car is moving with a speed of 25 m/s. How much work is required to stop the car?

Thanks

Answer 1

W = (0.5)*mf*vf^2 - (0.5)*mi*vi^2
Where f means final and the i means initial. In this case, vf is going to be zero, so then:
W = -(0.5)*mi*vi^2
W = -(0.5)*1500*(25)^2 = -468750 J

The negative sign indicates that the work is being done against the motion of the car.

Answer 2

you must reduce its kinetic energy to 0
KE= 1/2mv^2 = 1/2*1500*625= 468,759 Joules