physics 3!! **
posted by kelsey .
A man lifts a 3 kg crate from the floor to a shelf (2 m high) at constant speed*.
What was the change in KE of the crate?
What is the change in the PE of the crate?
If it takes 2 s for the man to lift the crate to the shelf, find the man's power output.
The energy (work) required to life any mass against a graviatational force is force*distance or mgh. This translates to a change of PE.
I will be happy to check your thinking.