Question

For a body of mass $1kg$, U-x graph is shown in the figure. If the body is released from rest at $x=2m$, then its speed when it crosses $x=5m$ is

• A. $2\sqrt{2}m{s}^{-1}$
• B. $1m{s}^{-1}$
• C. $2m{s}^{-1}$
• D. $3m{s}^{-1}$

Answer 1

The correct option is A $2\sqrt{2}m{s}^{-1}$

By energy conservation at $x=0$ and $x=5m$

$10=2+\frac{1}{2}m{v}^2+W.D$(from $x=1m$ to$x=3m$)

$8=\frac{1}{2}\times 1\times v^2+4\times 2\times \frac{1}{2}$

$\frac{1}{2}m{v}^2=4$

$v=2\sqrt{2}$