What situation would give you a mechanical advantage? *
A. sliding a chair across the room
B. using a fly swatter
C. lifting a large box
D. using a fixed-pulley system

D

Explanation:

In a fixed pulley system, there is load, carried bi the strings and also there is effort which is the number of the turns of strings or number of the wheels in the pulley system

Since

There is M.A in the fixed pulley system

But in other objectives, there is load but they lack effort, hence they cannot give mechanical advantage

work: w = fd (given)

work done by chet   =50*1 = 50 j

work done by mika =40*2 = 80 j

work done by sara =30*1.5 = 45 j

work done by bill =60*0.5 = 30 j

students in order from the greatest amount of work done to the least is mika> chet> sara> bill

hence option (b) is correct.