Question

A particle of mass $100$ g is thrown vertically upwards with a speed of $5$ m/s. The work done by the force of gravity during the time the particle goes up is :

• A. -0.5 J
• B. 0.5 J
• C. -1.25 J
• D. 1.25 J

Answer 1

Answer: (C)

-1.25 J

$Work$ $done$ $by$ $gravity$ $will$ $be$ $negative$ $times$ $gain$ $in$ $Potential$ $energy.$

$So,$ $Pontential$ $energy$ $is$ $given$ $by$ $mgh.$

$Using$ $formula$ $:$ $v^2$ = $u^2$ + $2as$

$\Rightarrow 0$ $=25+$ $2\times 10$

$s=1.25$

$So$ $the$ $work$ $done$ $by$ $gravity$ $will$ $be$ $-mgh$

= $-0.1\times 10$$\times 1.25$

= $-1.25J$