A man lifts a 17 kg crate directly upwards from the floor to a shelf (4 m high)

Question

A man lifts a 17 kg crate directly upwards from the floor to a shelf (4 m high) at constant speed*.
(*Neglect the very start and very end of the lift, where the crate would of course need to be accelerated from/to rest.)



d.) What was the change in kinetic energy of the crate?
-666.3431 J (this was incorrect)

e.) What is the change in the potential energy of the crate?
666.4  J (this was correct)

f.) Is mechanical energy conserved in this process? No (correct)

g.) Is the force the man exerts a conservative force? (no, correct)
(Make sure you understand why.)

h.) If it takes 3 s for the man to lift the crate to the shelf, find the man's power output.
222.133 W (correct)

I need the answer to part D  What was the change in kinetic energy of the crate?

Explanation / Answer

Change in the kinetic energy of the crate= 0 J

Since, the crate moves with a constant speed therefore its speed do not change hence, the change in kinetic energy is also zero.

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