## Answer :

Change in momentum = (force) x (time)

The initial momentum is (mass) x (speed) = 2500x 25 = 62,500 kg-m/s.

Since you want to

__stop__the vehicle, that number is also the required

*change*in momentum ... you want the vehicle to wind up with zero momentum.

62,500 = (force) x (time) = 20 x force

Divide each side by 20 :

force = 62,500 / 20 =

*3,125 newtons*