Question

A spring is kept compressed by a small trolley of mass $0.5kg$ lying on a smooth horizontal surface as shown in the adjacent fig. When the trolley is released, it is found to move at a speed $v=2m{s}^{-1}$. What potential energy did the spring possess when compressed?

• A. $2.0J$
• B. $0.25J$
• C. $1.0J$
• D. $10J$

Answer 1

Answer: (C)

$1.0J$

$K.E=0.5\times m\times v^2$
$K.E=0.5\times 0.5\times 4$
$K.E=1J$
As the work done is 1 J the same amount of energy will be stored in spring.