- #1
theloathedone
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Homework Statement
A man of weight W is in an elevator. The elevator accelerates vertically up at a rate a and at a certain instant has a speed V. The man then climbs a vertical ladder within the elevator at a speed v relative to the elevator. What is the man's rate of expenditure of energy?
Homework Equations
P = Fv
The Attempt at a Solution
So first, I found the apparent weight of the man as
[itex] w=W(1+\frac{a}{g}) [/itex]
which would be the force that he needs to exert in order to continue climbing.
I thought that the power required is just w*v (small v, the speed at which he is climbing in the elevator). But the answer states that it's w*(V+v), the total speed.
I was thinking that the power output should be the same whether the elevator just started to move and when it has already been accelerating for a certain time. So I'm not sure if the answer is wrong, or I've made a conceptual mistake.
Thanks in advance for the help!