Question

In an experiment to measure his power, a student records the time taken by him in running up a flight of steps on a staircase. Use the following data to calculate the power of the student :

Number of steps = 28
Height of each step = 20 cm
Time taken = 5.4 s
Mass of student = 55 kg
Acceleration = 9.8 m s⁻²
due to gravity

Answer 1

Mass of the student, (m₁) = 55 kg
Height of each step, (h) = 0.2 m
Number of steps, (n) = 28
So, total vertical height,
= (0.2) (28) m
= 5.6 m
Acceleration due to gravity, (g) = 9.8 m/s²
Time taken (t) = 5.4 s
We can calculate the work done against gravity as,
Work done by the car = (Weight of body) × (Vertical distance)
                                   = (55) × (9.8) × (5.6) J
                                   = 3018.4 J
Now, we can calculate the power of the boy as,
Power = ${\displaystyle \frac{\text{Work done}}{\text{Time}}}$
So ,
Power = ${\displaystyle \frac{3018.4}{5.4}}$ W
= 558.96 W
= 559 W 
So, the power is 559 W.