A200 kg roller coaster is located at the top of a hill where the height is 30 m. what is the velocity when it reches the bottom of the hill?

Assuming it starts at rest, the roller coaster only has potential energy at the top of the hill, which is

When it reaches the bottom, its potential energy will have converted to kinetic energy,

where is its velocity at that point. By the law of conservation of energy, assuming no loss of energy due to other sources (e.g. sound, heat), we have

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.

grav forces affect all objects magnetic forces affect magnetic objects and electric currents