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 in seconds. The force on the bullet becomes zero as soon as it leaves the barrel. What is the average impulse imparted to the bullet

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

Answer 1

The correct option is C 0.9 Ns

$F=600-2\times {10}^{5}t=0\Rightarrow t=3\times {10}^{-3}sec$
Impulse $I={\int }_0^{t}Fdt={\int }_0^{3\times {10}^{-3}}(600-2\times {10}^3)dt$
$=[600t-{10}^5{t}^2{]}_0^{3\times {10}^{-3}}=0.9N\times sec$