a parent pulls a sled and rider with a combine weight of 50kg up a 20-meter high hill and then gives the sled a push, providing an initial velocity of 4m/s. Frictional forces acting on the sled do 2000 joules of negative work as the sled moves down the hill. Find the total energy of this system.

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.

another example of kinetic energy would be,

kinetic energy   >     moving energy

answer   >   letter choice (c),   a hammer falling off a table.

hope that !                                         : )