Question

A bullet is fired from a gun. The force on the bullet is given by $F=600-2\times {{10}^{5}}t,$ where F is in newton and t is in second. The force on the bullet becomes zero as soon as it leaves the barrel. What is the average impulse imparted to the bullet?

• A. 9Ns
• B. Zero
• C. 0.9 Ns
• D. 1.8 Ns

Answer 1

Answer: (C)

0.9 Ns

Answer 2

$F=600-2\times {{10}^{5}}t$ At $t=0,$ $F=600N$ As $F=0,$ on leaving the barrel, $\therefore$ $0=600-2\times {{10}^{5}}t$ This is the time spent by the bullet in the barrel. Average force $=\frac{600+0}{2}=300\text{ }N$ $\therefore$ Average impulse imparted $=F\times t$ $=300\times 3\times {{10}^{-3}}=0.9Ns$