Question

A 59 kg man has a total mechanical energy of 150,023. J. If he is swinging downward and is currently 2.6 m above the ground, what is his speed ?

Answer 1

Answer:

$v = 70.95 \ m/s.$

Explanation:

Given data:

Mass of the man, $m = 59 \ kg$

Total mechanical energy, $E_{i} = 150,023 \ \rm J$

Height, $h = 2.6 \ m$

Suppose there is no external force acting on the man. In this situation, the total mechanical energy (kinetic + potential) will remain steady.

Let the speed of the man at 2.6 m be v.

Thus,

$E_{i} = E_{f}$

$E_{i} = \frac{1}{2}mv^{2} + mgh$

$150023 = 0.5 \times 59 \times v^{2} + 59 \times 9.80 \times 2.6$

$\Rightarrow \ v = 70.95 \ m/s.$