kg mass moving with a speed of 30 of 30ms-1 is brought to rest in 2.5sec, calculate the magnitude of the constant retarding force

Answer 1

a = -30/2.5 = -12 m/s^2
and as usual,
F = ma

Answer 2

V = Vo + a*t.
0 = 30 + a*2.5,
a = - 12 m/s^2.

F = M*a = 8 * (-12) =