Question

How long will it take a force of 10 N to stop a mass of 2.5 kg which is moving at 20 m/s ?

Answer 1

We are going to find acceleration
Force = mass × acceleration
`10 = 2.5 xx a`
⇒ `10/2.5 = a`
⇒ `(10 xx 10)/(2.5 xx 10) = a`
⇒ a = 4
Now , putting these values in the equation : 
`v = u + at`
⇒ `20 = 0 + 4 xx t`
⇒ 20 = 4t
⇒ `20/4 = t`
⇒ `t = 5s`