Question

A boy weighing $350N$ runs up a flight of $30$ steps, each $20cm$ high in $1$ minute. Calculate the work done.

• A. $2100J$
• B. $3500J$
• C. $210J$
• D. $700J$

Answer 1

The correct option is A $2100J$

As there are 30 steps with 20 cm each total distance would be 600 cm which is in general 6 m after conversion.

Given force = 350 N.

$Work=F\times S\times \cos \theta$.
$W=350\times 6\times \left(cos{180}^o\right)=-2100J$.

Hence a work of $2100J$ is done against gravity.