Aman whose mass is 80kg climbs a staircase in 20 seconds a expends a power of 120 watt. find the height of the staircase

3.06 m

Explanation:

The work done by the man against the gravity is given by

Where F is the force i.e. weight of the man and h is the displacement and is the angle between displacement and force

Since F=mg and is zero

W = mgh

Also, Work=power* time

Therefore, Power*time=mgh

Substituting power for 120 W, time for 20 seconds, g as 9.81 m/s2 and m as 80 Kg

120*20=80*9.81*h and making he the subject of the formula

Therefore, the height is approximately 3.06 m

the answer is f1 and d2 because if you put equal force on those two points the beam would balance trust me on this