Question

If a boy lifts a mass of 6kg to a height of 10m and travels horizontally with a constant velocity of 4.2m/s, calculate the work done? Explain your answer.

Answer 1

Answer:

W = 641.52 J

Explanation:

The work done here will be the sum of potential energy and the kinetic energy of the boy. Here potential energy accounts for vertical motion part while the kinetic energy accounts for the horizontal motion part:

$Work\ Done = Kinetic\ Energy + Potential\ Energy\\\\W = K.E +P.E\\\\W = \frac{1}{2}mv^2+mgh$

where,

W = Work Done = ?

m = mass = 6 kg

v = speed = 4.2 m/s

g = acceleration dueto gravity = 9.81 m/s²

h = height = 10 m

Therefore,

$W = \frac{1}{2}(6\ kg)(4.2\ m/s)^2+(6\ kg)(9.81\ m/s^2)(10\ m)$

W = 52.92 J + 588.6 J

W = 641.52 J