Jack and Jill
Classical Mechanics
Level
1
An old English nursery rhyme starts off "Jack and Jill went up the hill to fetch a pail of water". If the hill is 10 m high and Jack weighs 700 N, how much work in Joules did Jack need to do to get to the top of the hill?
The answer is 7000.
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1 solution
The work done is the force exerted times the distance traveled. In this case, Jack had to overcome the force of gravity (700 N) and traveled to the top of the hill (10 m). Hence he used 7 0 0 × 1 0 = 7 0 0 0 J of energy.