1. The problem statement, all variables and given/known data A mail bag with m = 120 kg is suspended by a vertical rope 8 m long. 1) I have to find the force needed to hold the bag in it's position. 2) I have to find out, how much work is done by the worker in moving the bag to this position. ----- 3) When a trolley is being pulled up a ramp 4 m, and the ramp inclines 30 degrees, find the work done by the normalforce. ----- 4) When a rope tied to a body is pulled, the body accelerates. But the body excerts an equal, opposite, force - is the total work done 0? 3. The attempt at a solution 1) I've found F = m*g*tan(a), where a is the angle between the vertical line and the string suspending the bag. 2) I thought of integrating m*g*tan(a) with limits 0 and 30 (degrees, cause 30 degrees is when x = 4 m) and multiplying by 4 m, since W = F*s. Please confirm. 3) I believe it's m*g*cos(30) * 4 m * cos(120) (120 degrees, because of 90 + 0). 4) I believe it is. But it's only an assumption.