For an object to remain at rest, which of the following must be true? a)The forces on it are balanced.

b)There is not friction

c)Gravity does not act on it

d)The object has no mass.

A

Explanation:

If the forces are balanced, it will sty in the same spot. Lets say a little bit of mass was directed on a side or a object, it might end up falling.

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.

the displacement produced by the body.  

the amount of force subjected to the body.  

the angle between the direction of force and displacement