a pupil of mass 50 kg runs a flight of 20 stairs each 25cm high in a time of 20 seconds (take g= N/kg calculate the pupil s gain in potential energy

answer

PE = mgh

so, how high did she go?

the time does not matter, unless you want the power, which is work/time

oh, yeah -- don't bother making a second post just insisting on an answer. It's annoying, and won't get any faster response.

Please work it out for me, please help me✍️

To calculate the pupil's gain in potential energy, we first need to find the change in height and then multiply it by the pupil's mass. Here's how:

1. Calculate the change in height (Δh):
The height of each stair is given as 25 cm. Since the pupil runs a flight of 20 stairs, the total change in height is:
Δh = 20 stairs * 25 cm/stair

Now, convert the change in height to meters by dividing it by 100 (since 1 meter = 100 cm):
Δh = (20 stairs * 25 cm/stair) / 100 cm/m

Simplify the equation:
Δh = 5 m

2. Calculate the pupil's gain in potential energy (ΔPE):
The potential energy (PE) is given by the equation: PE = m * g * h,
where m is the mass, g is the acceleration due to gravity, and h is the change in height.

Given:
Mass (m) = 50 kg
Acceleration due to gravity (g) = 9.8 N/kg
Change in height (Δh) = 5 m (from step 1)

Substitute the values into the equation:
ΔPE = m * g * Δh
ΔPE = 50 kg * 9.8 N/kg * 5 m

Calculate the result:
ΔPE = 2450 N.m or 2450 J (joules)

Therefore, the pupil's gain in potential energy while running up the stairs is 2450 joules.