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

Explanation

Here m = 20 kg , F = - 50 N (retardation force )
As F = ma
`implies` a = f/m = -50/20 = -2.5 `ms^(-2)`
Using equation , v = u + at
Given , u = 15 `ms^(-1) `, v = 0
Now, 0 = 15 + (-25) t
or t = 6 s.