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Work done climbing a flight of stairs.

  • Thread starter fattydq
  • Start date
79
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A 58 kg firefighter climbs a flight of stairs 5.3 m high. How much work is required?

I know work is just force times distance, but I'm not given a force? And I can't really find a force because force is mass times acceleration and I'm not given an acceleration...help!
 

mgb_phys

Science Advisor
Homework Helper
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Do you know about gravitational potential energy?

Actually you are given a force, if he has a mass of 58kg (you must have some skinny firemen!) and he is on Earth, how much does he weigh?
 
79
0
Do you know about gravitational potential energy?

Actually you are given a force, if he has a mass of 58kg (you must have some skinny firemen!) and he is on Earth, how much does he weigh?
9.8 times 58...so 568.4 N right? Then 568.4 times 5.3m and you get 3012.52, yes? Would the unit be joules?
 

mgb_phys

Science Advisor
Homework Helper
7,744
11
Yes - but think about how many significant figures you should have

The equation for potential energy = m g h
As you said this is the same as force (mg) * distance (h)
And yes J = N m = kg m^2/s^2
 
79
0
Would it just be 3.0 times 10^3 in correct sig figs?
 
Last edited:
79
0
?????
 

mgb_phys

Science Advisor
Homework Helper
7,744
11
Yes, you have 2 sig figures for the mass and height so it's two sig figures for the answer.
So formally 3.0 x 10^3 J or 3000J would probably be ok.
 

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