Question

A ship of mass $3\times {10}^{7}kg$ initially at rest is pulled by a force of $5\times {10}^{4}N$ through a distance of $3m$. Assume that the resistance due to water is negligible. The speed of the ship is

• A. $1.5m/s$
• B. $60m/s$
• C. $0.1m/s$
• D. $5m/s$

Answer 1

The correct option is C $0.1m/s$

Mass of the ship $m=3\times {10}^{7}kg$
Force on the ship $F=5\times {10}^{4}N$
Using Newton's second law,
$F=ma$
$\Rightarrow a=\frac{5\times {10}^4}{3\times {10}^7}=\frac{5}{3}\times {10}^{-3}m/s^2$
From 3rd equation of motion, $v^2-u^2=2as$ and $u=0$
$\Rightarrow v^2=2\times \frac{5}{3}\times {10}^{-3}\times 3\Rightarrow v^2={10}^{-2}\Rightarrow v={10}^{-1}=0.1m/s$