A child does 350 J of work while pulling a box from the ground up to his tree house at a steady speed with a light rope. The tree house is $4.0 \mathrm {~m}$ above the ground. What is the mass of the box?
A) 8.9 kg
B) 5.3 kg
C) 6.7 kg
D) 8.0 kg

Question

Quizplus · Accepted Answer

The work done (350 J) is equal to the gravitational potential energy gained by the box, which is $mgh$. Given $h = 4.0 \, \text{m}$ and $g = 9.8 \, \text{m/s}^2$, we can solve for $m$: $350 = m \times 9.8 \times 4.0$. Solving for $m$ gives approximately 8.9 kg.

A Child Does 350 J of Work While Pulling a Box