Sean, whose mass is 60 kg, is riding on a 5.0 kg sled initially traveling at 8.0 m/s. He brakes the sled with a constant force, bringing it to a stop in 4.0 s. What force does he apply?

Explanation:

according to Newtons second law;

F = ma

F = m(v-u)/t

m is the mass = 60+5 = 65kg

v is the final velocity = 0m/s

initial velocity = 8m/s

time t = 4.0s

F = 65(8)/4

F = 65*2

F = 130N

Hence he applied a force of 130N

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