Question

Calculate the braking force to bring a body of mass 1kg to rest from 25m/s on a level ground in 60m with uniform retardation?

Answer 1

If it takes t seconds, then we have
25-at = 0
25t - 1/2 at^2 = 60
Solve that for a, and then as usual, F=ma

Answer 2

V^2 = Vo^2 + 2a*d = 0,
25^2 + 2a*60 = 0,
a = -5.2 m/s^2.

F = M*a = 1 * (-5.2) = -___N.
The negative sign means the force opposes the motion.