If the kinetic energy possessed by a man of 50kg is 625j , the speed of man is

v= 5 m/s

Explanation: Solution:

KE= 1/2 mv²

Derive to find v.

v = √ 2KE / m

Substitute the values

v = √2x 625 J / 50 kg

= √ 1250 J / 50 kg

= √ 25 kg. m/s /kg

= 5 m/s

Unit for J can be expressed in kg.m/s so we cancel kg and the remaining unit is m/s.

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.