A bullet of mass 20 g has an initial speed of 1 m s- 1 , just before it starts penetrating a mud wall of thickness 20 cm . If the wall offers a mean resistance of 2.5× 10- 2 N, the speed of the bullet after emerging from the other side of the wall is close to:

Question

A bullet of mass 20 g has an initial speed of 1 m s- 1 , just before it starts penetrating a mud wall of thickness 20 cm . If the wall offers a mean resistance of 2.5× 10- 2 N, the speed of the bullet after emerging from the other side of the wall is close to: (A) 0.7 m s- 1 (B) 0.3 m s- 1 (C) 0.1 m s- 1 (D) 0.4 m s- 1

Tardigrade Admin · Accepted Answer

a=-(2.5 × 10- 2/20 × 10- 3)=-(5/4)ms- 2 From v2-u2=2as v2=u2+2as v=√12 - 2 × (5/4) × 20 × 10- 2 =√0.5 =0.7ms- 1

Q. A bullet of mass $20 g$ has an initial speed of $1 m s^{- 1}$ , just before it starts penetrating a mud wall of thickness $20 c m$ . If the wall offers a mean resistance of $2.5 \times 1 0^{- 2} N,$ the speed of the bullet after emerging from the other side of the wall is close to:

$0.7 m s^{- 1}$

$0.3 m s^{- 1}$

$0.1 m s^{- 1}$

$0.4 m s^{- 1}$

$a = - \frac{2.5 \times 1 0 ^{- 2}}{20 \times 1 0 ^{- 3}} = - \frac{5}{4} m s^{- 2}$
From $v^{2} - u^{2} = 2 a s$
$v^{2} = u^{2} + 2 a s$
$v = 1^{2} - 2 \times \frac{5}{4} \times 20 \times 1 0^{- 2}$
$= 0.5$
$= 0.7 m s^{- 1}$

Q. A bullet of mass 20g has an initial speed of 1ms−1 , just before it starts penetrating a mud wall of thickness 20cm . If the wall offers a mean resistance of 2.5×10−2N, the speed of the bullet after emerging from the other side of the wall is close to:

0.7ms−1

0.3ms−1

0.1ms−1

0.4ms−1