Question

A boy weighing 150N runs a. up and b.)down a flight of stairs, the vertical distance between the floor is 5.5m . How much work is done by gravity?

Answer 1

a-W= -mgh= (-150*5.5) since work is done against direction of gravity
b- W= mgh =150*5.5 since work is done in direction of gravity

Answer 2

how can i get tha angle of up and down?

Answer 3

use cosine and sine ratio

Answer 4

how i will compute the angle if the given was the force and h of the vertical distance of the floor?

Answer 5

You cant. But you don't need to. Since gravity acts only in the vertical you don't need the angle or the horizontal distance to calculate your answer.

Answer 6

thank you!