A bullet of mass 200 g having initial kinetic energy 90 J is shot inside a long swimming pool as shown in the figure. If it's kinetic energy reduces to 40 J within 1 s, the minimum length of the pool, the bullet has a to travel so that it completely comes to rest is

Question

A bullet of mass 200 g having initial kinetic energy 90 J is shot inside a long swimming pool as shown in the figure. If it's kinetic energy reduces to 40 J within 1 s, the minimum length of the pool, the bullet has a to travel so that it completely comes to rest is (A) 45 m (B) 90 m (C) 125 m (D) 25 m

Tardigrade Admin · Accepted Answer

Using mv =√2 mk u =(1/0.2) √2 × 0.2 × 90=30 m / s v =(1/0.2) √2 × 0.2 × 40=20 m / s a =(20-30/1)=-10 m / s 2 s =(- u 2/2 a )=45 m

Q. A bullet of mass $200 g$ having initial kinetic energy $90 J$ is shot inside a long swimming pool as shown in the figure. If it's kinetic energy reduces to $40 J$ within $1 s$ , the minimum length of the pool, the bullet has a to travel so that it completely comes to rest is

$45 m$

$90 m$

$125 m$

$25 m$

Using $m v = 2 mk$
$u = \frac{1}{0.2} 2 \times 0.2 \times 90 = 30 m / s$
$v = \frac{1}{0.2} 2 \times 0.2 \times 40 = 20 m / s$
$a = \frac{20 - 30}{1} = - 10 m / s^{2}$
$s = \frac{- u ^{2}}{2 a} = 45 m$

Q. A bullet of mass 200g having initial kinetic energy 90J is shot inside a long swimming pool as shown in the figure. If it's kinetic energy reduces to 40J within 1s, the minimum length of the pool, the bullet has a to travel so that it completely comes to rest is

45m

90m

125m

25m