Question

A bullet of $5g$, travelling at a speed of $100m/s$ penetrates a wooden block up to $6.0cm$. Then the average force applied by the bullet on the block is:

• A. $417N$
• B. $8333N$
• C. $83,3N$
• D. $Zero$

Answer 1

Answer: (A)

Initial kinetic energy $K.E_i=\frac{1}{2}m{v}^2=\frac{1}{2}\left(0.005\right)(100{)}^2=25J$

Final velocity of bullet $v_f=0$

So, final kinetic energy $K.E_f=0$

Distance covered in block $S=6cm=0.06m$

Force exerted by bullet $FS=|K.E_f-K.E_i|$

Or $F\times 0.06=|0-25|$

$⟹F=417N$