Physics of Running (Part II)

Today, i will be talking about the theory of pendulums. As you all know, during running, our legs and arms work as pendulums. How? Let me explain it that to you.

First of all, a pendulum is a weight, hung from a fixed point so that it can swing forward and backward easily like shown in the diagram above. There is an important thing we need to know about pendulums which is, the fact that the mass of the bob does NOT affect the speed of the pendulum. It is the length of the rod that matters most because the shorter the rod, the faster it travels. This is due to the gravitational rate of all objects, which is about 9.8m/s. This means that all objects fall at a speed of 9.8m/s, no matter how much it weighs.

You may be thinking, why would a shorter length make the speed of the pendulum to increase? This is because, a short pendulum has a narrower arc, and is able to convert G.P.E to K.E in a shorter period of time.

Now, lets apply this to your legs.

Imagine your legs as two pendulums. Your feet is the bob and your hip is the pivot. Think about it. If you run with your knees locked, it would be harder than if you ran with your knees bent. The rate of converting G.P.E to K.E is very low because you can't bring your legs up high but with your knees bent, you would be able to bring up your legs much higher to achieve more P.E.

If you look at some of the best sprinter, you would see that they raise their knees up high during a race. This makes them faster.