Power Stairs Problem: 690 W Needed for 44 kg Person to Climb 12 Flights in 15s

[sweedeljoseph]

Homework Statement

How much power is needed for a 44 kg person to climb 12 flights of stairs that each have a height of 2 meters, in a time of 15 seconds?

Homework Equations

P=W/T

The Attempt at a Solution

answer from the teacher is 690 W. i remember doing the something like this in class but i don't remember exactly what all to do. wouldn't you multiply 12 by 2 so its total distance then multiply it by the 15 for the total time? or is that just time in general, the total? then put it into the power equation? i know youre supposed to convert the mass into N but that's it. I am so lost please help me.

thank you!
sweedeljoseph

 

[asleight]

Homework Statement

How much power is needed for a 44 kg person to climb 12 flights of stairs that each have a height of 2 meters, in a time of 15 seconds?

Homework Equations

P=W/T

The Attempt at a Solution

answer from the teacher is 690 W. i remember doing the something like this in class but i don't remember exactly what all to do. wouldn't you multiply 12 by 2 so its total distance then multiply it by the 15 for the total time? or is that just time in general, the total? then put it into the power equation? i know youre supposed to convert the mass into N but that's it. I am so lost please help me.

thank you!
sweedeljoseph

U_0+W=U_f\rightarrow W=\Delta U. Then, use your relevant equation to solve.

 

[sweedeljoseph]

whats U initial? or U final?

 

[Saladsamurai]

sweedeljoseph, there is probably more than one way to solve this. You have the key equation P=W/t

Yes, t is the TOTAL time

Now you just need to find the Work. Work is defined as Force*displacement

You found the displacement to be 24 meters.

What is the force in this case?

Casey

 

[sweedeljoseph]

well force is in N and you can make the mass into Newtons. mass is 44 kg so times 9.8 its 431.2 N. so I am guessing that's the force?

i just put it in the calculator. it works! thank you. for some reason i kept thinking W was weight instead of work. i feel stupid haha.

thank you!
sweedeljoseph