A 48 kg woman climbs a flight of stairs 12 m high in 30 s. How much power does she use?

1 answer

To calculate the power used by the woman, we can use the formula for power, which is:

\[ \text{Power} = \frac{\text{Work}}{\text{Time}} \]

First, we need to calculate the work done against gravity when she climbs the stairs. The work done (W) can be computed using the formula:

\[ W = m \cdot g \cdot h \]

where:

  • \(m\) is the mass (48 kg),
  • \(g\) is the acceleration due to gravity (approximately \(9.81 , \text{m/s}^2\)),
  • \(h\) is the height (12 m).

Now, we can calculate the work done:

\[ W = 48 , \text{kg} \cdot 9.81 , \text{m/s}^2 \cdot 12 , \text{m} \]

Calculating this step-by-step:

  1. Calculate \(48 \cdot 9.81\):

    \[ 48 \cdot 9.81 \approx 470.88 , \text{N} \]

  2. Now multiply by 12 m:

    \[ W \approx 470.88 , \text{N} \cdot 12 , \text{m} \approx 5666.56 , \text{J} \]

Next, we calculate the power by dividing the work done by the time taken (30 s):

\[ \text{Power} = \frac{5666.56 , \text{J}}{30 , \text{s}} \approx 188.85 , \text{W} \]

Thus, the power used by the woman while climbing the stairs is approximately 188.85 watts.