A crane lifts a 400 N crate full of baked beans 15 m. How much work was done by the crane?
1 answer:
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Answer:
Explanation:
By conservation of energy, the sum of the kinetic and gravitational potential energies at the surface of the Earth must be equal than their sum at infinity, so we have:
Where is the gravitational constant,
and
are the mass and radius of the Earth, <em>m </em>is the mass of the particle,
its velocity at the surface of the Earth (which would be its escape velocity) and
and
are the velocities and distance at infinity, which would be null and infinity respectively, so the right hand side of our equation is 0J, which leaves us with:
Also, since the force the molecule experiments is the force of gravity (disregarding drag), we can write its weight in terms of Newton's Law of Gravitation:
Which means that:
So finally putting all together we can write: