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Simple Machines: Running Up Ramps

Continuing his series on simple machines, Everyday Einstein looks at the physics behind inclined planes, otherwise known as ramps.

By
Lee Falin, PhD,
May 17, 2013
Episode #054

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I have a confession to make: I’m a physics degree dropout.

Before I entered the realm of biology and computational genetics, I was, for a single semester, a physics major. You see, I really love Star Trek, and I was pretty sure that I would be well on my way to inventing the first warp drive. Unfortunately, all we seemed to talk about in physics were things that rolled down ramps. No warp drive, no disrupters, not even a lightsaber; just one thing after another rolling down ramps. But today, I’ve decided to bring my scientific learning full circle and talk about the next simple machine on our list: the inclined plane.

A Ramp by Any Other Name…

The first thing to realize is that “inclined plane” is just a fancy word for ramp. You see inclined planes in lots of places: slides at the playground, wheelchair ramps, loading ramps on trucks, roller coaster rides, and a few unexpected places as well.

Let’s review for a moment a few basic facts from the last time we talked about simple machines. In the episode Pulling with Pulleys, we mentioned that simple machines are “force multipliers.” This means that usually the force you put into them gets multiplied when it comes out. The amount by which it gets multiplied is called the “mechanical advantage.”

In the episode All Work and No Play we discussed that in science, work is equal to force times distance, and that the amount of work you do is equal to the amount of energy you spend.  The law of conservation of energy doesn’t allow our simple machine to increase the amount of energy we provide, so in order to multiply our force, it exacts a heavy toll. A simple machine trades force for distance, meaning that to do the same amount of work with more force, we have to increase the distance that we move.

Let’s look at some examples involving inclined planes.

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