How many Joules does a 110 kg person expand in climbing 440 m of stairs?

Answer 1

We could use (force x distance) to calculate the work, or (mass x gravity x height). Let's avoid using the force (weight) since it involves looking up another unit and carrying out another step in the arithmetic. Note: We have to assume that the given 440 m is the net vertical rise of the stairs, since the question tells us nothing about their slope or pitch. On that basis, we also note that this is one heckuva climb, being within 10 ft of the officially listed height-above-street for the Willis (Sears) tower in Chicago, and not made any easier by the fact that our climber is no lightweight. (110 kg weighs about 243 lbs.) But we're not going to worry about any of that; we'll just crunch the numbers given. Work = change in potential energy = M x G x H M = 110 kg G = 9.78 m/s2 H = 440 m M x G x H = (110 kg x 9.78 m/s2 x 440 m) = (110 x 9.78 x 440) (kg - m2 / s2) = 473,352 Newton-meter = 473,352 Joules If our hero can lift his weight at the rate of one horsepower, this quantity of work will take almost 11 minutes. Another Note: This is the net increase in gravitational potential energy due to having changed the elevation of his 110 kg of mass. But the man is certain to have expended a whole lot more energy than this in the effort, and we have no way of knowing exactly how much. It all depends on the style, form, and efficiency of his stair climbing technique. No two people are the same, which is why some can run a marathon without breaking a sweat, while I have to slow down and take deep breaths after typing a long Wiki.Answer like this one on the keyboard.