A bullet of mass 20 g has an initial speed of 1 ms–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 :

Engineering

Physics

Straight Line Motion

Question

A bullet of mass 20 g has an initial speed of 1 ms^–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 :

0.4 ms^–1

0.1 ms^–1

0.3 ms^–1

0.7 ms^–1

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$2 .5 \times 10^{- 2} \times 0 .2 = \frac{1}{2} \times 20 \times 10^{- 3} {- V^{2} + 1^{2}}$

$5 \times 10^{- 3} = 10 \times 10^{- 3} (1 - V^{2})$

$1 - V^{2} = \frac{1}{2}; V^{2} = \frac{1}{2}; V = \frac{1}{\sqrt{2}} = 0 .7$