Is Using a Stair Machine the Same as Climbing Stairs?

Since nan alteration successful kinetic power is still zero, this intends that nan affirmative alteration successful gravitational imaginable power is adjacent to nan antagonistic of nan alteration successful soul energy. Let's opportunity you person a wide of 75 kilograms (165 pounds). That intends moving up 1 metre would trim your soul power by 735 joules. That's called moving out.

Climbing Stairs vs. a Stair Climber

Now we tin spell backmost to nan original question: What does nan work-energy rule opportunity astir stairs versus a stair-climbing machine? Well, we already did nan physics of step climbing. It's nan aforesaid calculation if you get connected apical of a 1 metre array aliases climb 100 stories—it's conscionable a different worth for nan height. But suppose you enactment successful nan aforesaid spot while nan stairs move nether you. If personification is measuring your guardant motion, they’d opportunity your velocity is zero. Your tallness besides doesn't change, truthful now nan work-energy equation looks for illustration this:

This says nan alteration successful soul power is besides zero, which intends you don't pain any calories. I mean, that can’t beryllium correct … right? Then really do we hole this? I'm going to usage a bully illustration based connected this video from Steve Mould. It goes for illustration this: Imagine you are climbing up a downward-moving escalator. Again, an perceiver connected nan crushed would spot you arsenic stationary. However, we could besides measurement your velocity from nan reference framework of nan escalator, and you would beryllium moving up.

In fact, if nan escalator had walls and a ceiling, you wouldn't beryllium capable show that you were staying successful place. You wouldn't moreover cognize nan stairs are moving. Since nan stairs are moving astatine a changeless velocity (zero acceleration), this would beryllium an inertial reference frame. In physics, immoderate inertial reference framework is arsenic valid arsenic immoderate different reference frame—the basal laws of physics stay nan same. So, from nan position of nan escalator framework you are moving up and doing work. It's nan aforesaid arsenic if you were stepping up a stationary frame.

But Actually, nan Stair Climber Is Harder

I said that nan step climber and climbing stairs were nan same—but they are not. In fact, climbing up 100 stories is easier than nan balanced region connected a step climber. Does that look crazy? It is simply a small crazy. The logic they’re different is because nan gravitational section (g) is ne'er really constant.

Remember, we defined nan gravitational imaginable power arsenic U = m x g x y? That's not really wrong, but it is simply a small misleading. Actually, nan gravitational imaginable power for nan Earth-person strategy would beryllium defined arsenic nan following: