Question

A constant retarding force of 50 N is applied to a body of mass 20kg moving initially with a speed of 15ms^-1. How long does the body take to stop?

Answer 1

Acceleration, a =\(-\frac{50N}{20kg}\) = -2.5ms^-2

[Negative sign indicates retardation]

u = 15ms^-1, v = 0, t = ?

v = u + at

0 = 15 – 2.5t or 2.5t = 15 or

t = \(\frac{15}{2.5}\)s = 6.0s