Question

A weightlifter goes to lift a 100 kg bar over her head which is 2.0 m in the air. How much work did the weightlifter do to lift the bar?​

Answer 1

Answer:

$W = -1960 \ \rm J$

Explanation:

Given data:

Mass of the bar, $m = 100 \ kg$

Height, $h = 2.0 \ m$

The work done by the weightlifter can be expressed as,

$W = F.h\textrm{cos} \theta$

Here,

F = mg

$\theta$ = angle between the fore and the vertical displacement which $180^{\circ}.$

Thus,

$W = 100 \times 9.80 \times 2.0\textrm{cos} 180^{\circ}$

$W = -1960 \ \rm J.$