A block is on a surface with µs=0.276. It takes 1.11 N to break it free from static friction. What is the mass of the block?

0.407 kg

Explanation:

Given :

Coefficient of static friction, µs = 0.276

Force, F = 1.1 N

Using the relation :

μ = F/N

N = normal reaction ; N = mg

μ = F / mg

g = acceleration due to gravity = 9.8 m/s²

0.276 = 1.1 / m * 9.8

0.276 = 1.1 / 9.8m

0.276 * 9.8m = 1.1

2.7048m = 1.1

m = 1.1 / 2.7048

m = 0.4066844

Mass = 0.407 kg

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.

prolly a beacuse the momentuem the car has increases while going down hill