Question

A body with mass $2 kg$ moves in one direction in the presence of a force which is described by the potential energy graph. If the body is released from rest at $x = 2 m,$ then its speed when it crosses $x = 5 m$ is

• A. zero
• B. $1\, ms^{-1}$
• C. $2\, ms^{-1}$
• D. $3\, ms^{-1}$

Answer 1

Answer: (C)

Let at $x=2\, m ,\, U=U_{2}$
$\frac{10-U_{2}}{2-1}=\frac{10-0}{3.5-1}$
$\Rightarrow U_{2}=6\, J$
$(K E+P E)_{x=2\, m }=(K E+P E)_{x=5\, m }$
$\Rightarrow 0+6=\frac{1}{2}(2) v^{2}+2$
$\Rightarrow v=2\, m / s$