Suppose you have a 113-kg wooden crate resting on a wood floor. (μk = 0.3 and μs = 0.5). What maximum force (in N) can you exert horizontally on the crate without moving it?

554.265 N

Explanation:

Without moving it means it is static. Since we know that normal friction is given by N=mg where m is the mass and g is acceleration due to gravity.

The static friction will then be given by multiplying the normal reaction by the coefficient of static friction. Taking g as 9.81, m as 113 kg and 0.5 for coefficient of static friction then

Fs= 0.5*113*9.81=554.265 N

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.