Question

In a children's park, there is a slide which has a total length of 10 m and a height of St m (figure 8-E3). Vertical ladder are provided to reach the top. A boy weighing 200 N climbs up the ladder to the top of the slide and slides down to the ground. The average friction offered by the slide is three tenth of his weight. (a) the work done by the boy on the ladder as he go: up, (b) the work done by the slide on the boy as he cornea down, (c) the work done by the ladder on the boy as he goes up. Neglect any work done by forces inside the body of the boy.

Answer 1

$l=10m,h=8m,mg=200N$

$F=200\times \left(\frac{3}{10}\right)=60N$

(a) Work done by the boy on the lader

$W_b=\left(mgsin\theta \right)\times 10$

$=200\times (\frac{8}{10}\times 10)$

$1600J$

When the boy is going up because the work is done by himself.

(b) Work done against frictional force,

$W=\mu RS=fl=(-60)\times 10$

$=-600J$

(c) Work done by the leader on the boy is zero.

When the boy is going up because the work is done by himself