Explanation

(d) Initial velocity of steel ball $u = 14\ {ms}^{- 1}$
Mass of steel ball $m = 0.5$ kg
Force acting on the steel ball from opposite direction.
$F = - 1200\ N$
Time duration for collision,
$t = 25\ ms = 25 \times 10^{- 3}\ s$
Let final velocity of ball$= v$
Applying Newton’s II law of motion to steel ball $ie,$
[image:5_image265.emf]
$F = \frac{p_{2} - p_{1}}{t}$
$\Longrightarrow \ - 1200 = \frac{mv - mu}{t}$
$\Longrightarrow \ \ \frac{- 1200}{m} + u = v$
$\Longrightarrow \ \ v = \frac{- 1200 \times 25 \times 10^{- 3}}{0.5} = - 60\ {ms}^{- 1}$
$v = - 60 + 14\ {ms}^{- 1}$
$= - 46\ {ms}^{- 1}$
[$-$ve sign shows that now ball will move in the direction of force]