Is Using a Stair Machine the Same as Climbing Stairs?

For the reason that change in kinetic power remains to be zero, which means the constructive change in gravitational potential power is the same as the damaging of the change in inside power. As an example you could have a mass of 75 kilograms (165 kilos). Meaning shifting up 1 meter would scale back your inside power by 735 joules. That is known as understanding.

Climbing Stairs vs. a Stair Climber

Now we will return to the unique query: What does the work-energy precept say about stairs versus a stair-climbing machine? Properly, we already did the physics of stair climbing. It is the identical calculation for those who get on prime of a 1 meter desk or climb 100 tales—it is only a completely different worth for the peak. However suppose you keep in the identical place whereas the steps transfer underneath you. If somebody is measuring your ahead movement, they’d say your velocity is zero. Your peak additionally does not change, so now the work-energy equation seems like this:

This says the change in inside power can also be zero, which implies you do not burn any energy. I imply, that may’t be proper … proper? Then how can we repair this? I’ll use a pleasant instance based mostly on this video from Steve Mould. It goes like this: Think about you’re climbing up a downward-moving escalator. Once more, an observer on the bottom would see you as stationary. Nonetheless, we might additionally measure your velocity from the reference body of the escalator, and you’ll be shifting up.

The truth is, if the escalator had partitions and a ceiling, you would not have the ability inform that you simply have been staying in place. You would not even know the steps are shifting. For the reason that stairs are shifting at a continuing velocity (zero acceleration), this is able to be an inertial reference body. In physics, any inertial reference body is as legitimate as another reference body—the fundamental legal guidelines of physics stay the identical. So, from the angle of the escalator body you are shifting up and doing work. It is the identical as for those who have been strolling up a stationary body.

However Really, the Stair Climber Is More durable

I mentioned that the stair climber and climbing stairs have been the identical—however they don’t seem to be. The truth is, climbing up 100 tales is simpler than the equal distance on a stair climber. Does that appear loopy? It’s a little loopy. The explanation they’re completely different is as a result of the gravitational area (g) isn’t actually fixed.

Bear in mind, we outlined the gravitational potential power as U = m x g x y? That is not likely improper, however it’s a little deceptive. Really, the gravitational potential power for the Earth-person system can be outlined as the next: