A bullet of mass 0.04 kg moving with a speed of 90 m/ s enters a heavy wooden block and is stopped a

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4-1.Newton's Laws of Motion

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A bullet of mass $0.04\; kg$ moving with a speed of $90\; m/ s$ enters a heavy wooden block and is stopped after a distance of $60\; cm$. What is the average resistive force exerted by the block on the bullet?

Option A

Option B

Option C

Option D

Solution

Answer The retardation $a$ of the bullet (assumed constant) is given by

$a=\frac{-u^{2}}{2 s}=\frac{-90 \times 90}{2 \times 0.6} \,m\, s ^{-2}=-6750 \,m\,s ^{-2}$

The retarding force, by the second law of motion, $1\, s$

$=0.04 \,kg \times 6750 \,m \,s ^{-2}=270\, N$

The actual resistive force, and therefore, retardation of the bullet may not be uniform. The answer therefore, only indicates the average resistive force.

Standard 11

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medium

A bullet of mass $0.04\; kg$ moving with a speed of $90\; m/ s$ enters a heavy wooden block and is stopped after a distance of $60\; cm$. What is the average resistive force exerted by the block on the bullet?

Solution

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