Question

A constant retarding force of 50 N is applied to a body of mass 10 kg moving initially with a speed of $10ms^{- 1}$. The body comes to rest after

• A. 2 s
• B. 4 s
• C. 6 s
• D. 8 s

Answer 1

Answer: (A)

2 s

Answer 2

Here, F = -50 N

(-ve sing for retardation

$m = 10kg,u = 10ms^{- 1},v = 0$

As F = ma+ +++++

$\therefore a = \frac{F}{m} = \frac{- 50}{10kg} = - 5ms^{- 2}$

Using $v = u + at$$$\therefore t = \frac{v - u}{a} = \frac{0 - 10ms^{- 1}}{- 5ms^{- 2}} = 2s$$