At what minimum rate is a 60.0-kg boy using energy when, in 8.00 s, he runs up a flight of stairs that is 10.0-m high?
A) 75.0 W
B) 48.0 W
C) 735 W
D) 4.80 kW

Question

Quizplus · Accepted Answer

The minimum rate at which the boy is using energy can be calculated using the formula for power, which is $P = \frac{W}{t}$, where $P$ is power in watts (W), $W$ is work done in joules (J), and $t$ is time in seconds (s). The work done by the boy can be found using the formula for gravitational potential energy, which is $W = mgh$, where $m$ is mass in kilograms (kg), $g$ is the acceleration due to gravity (9.8 m/s$^2$), and $h$ is height in meters (m). Substituting the given values, we get $W = 60.0 \, \text{kg} \times 9.8 \, \text{m/s}^2 \times 10.0 \, \text{m} = 5880 \, \text{J}$. Then, the power is $P = \frac{5880 \, \text{J}}{8.00 \, \text{s}} = 735 \, \text{W}$.

At What Minimum Rate Is a 60