# Power needed to lift the average American man 3 stories

2.28.seconds is quick from stand still. What power will be needed to stop him there? Does it throw your equation. Out of wack to change time and save power by coasting in to 0 velocity at peak? Or would you prefer to increase initial acceleration to stay with in that time.

jbriggs444
Homework Helper
2019 Award
2.28.seconds is quick from stand still. What power will be needed to stop him there?
It does not take power to stop him. It releases power.

OmCheeto
Gold Member
This problem reminds me of a video I once saw:

It looks like it took the bucket about 3 seconds to get to the 4th story. (12 meters?)
Has anyone seen a physics analysis of this video, here at the forum?
I haven't done a pulley homework problem in about 30 years, so off the top of my head, I have no idea how that worked.

 tag: Crazy Construction Worker

It does not take power to stop him. It releases power.
Oh was his inertia taken into account in the equation? Didn't realize that. At that speed of travel or any speed for that matter removing the power isn't going to result in an immediate stop, he would travel another 8 ft +- beyond his 3rd story destination if power was removed at that point. Certainly his energy should be captured to reduce consumption in these green times.

mfb
Mentor
Oh was his inertia taken into account in the equation? Didn't realize that.
If we wouldn't take it into account, stopping would not be relevant.
It does not matter how he slows down - friction, regenerative braking, whatever - it doesn't exceed the +3.5 kW constraint.