Physics is what drives the skates, be it the traditional roller skates or the new age inline skates. The world is all about science. And when it comes to talking about the science behind working of things, it is physics bang on.
Newton’s law of motion are comprised of three basic laws. Instead of going from laws 1 to 3, let us go in the order of how the skater begins skating and finally stops. This way the understanding of underlying laws becomes easy.
Starting the skating process
The skater begins the process of skating by pushing the toes and heels on the ground, opposite to the direction in which he/she wants to move. Here the energy from the muscles (potential energy) is transferred to the wheels (kinetic energy) of the skates. The skater moves because, the ground exerts an equal and opposite force to the wheels, thereby making it spin.
This is governed by Newton’s third law of motion which states that, “Every action has an equal and opposite reaction”. The action here was to push the ground with the skates and the equal and opposite reaction was to push the skater forward.
While this happens, the wheels spin because of a torque which is produced by friction from the ground. This friction is called static friction. This force causes one surface to slide over the other. It happens so that when the roller blades move forward, the surface of Earth moves backwards to let the skater move. Sounds bizarre?! Well, the Earth is so huge that you hardly notice that it is going few millimetres to the other side!
Repeating the process to gain speed
To go on this entire process is repeated over and over again to gain speed. This is governed by Newton’s second law which states, “The rate of change of momentum is proportional to the imposed force and goes in the direction of the force”. It means if you push twice as hard, the acceleration is going to be twice as much.
It also indicates that if you push the other way, you will decelerate, that is, reduce your speed. It also suggests that heavier the body (or the person), more force is required to accelerate. Hence, lighter the person, faster is the acceleration going to be.
Gliding with momentum
After a while the skater will start gliding or coasting. This occurs solely based on momentum gathered from the high speed gained earlier.
Newton’s first law of motions states this as, “A body remains at rest or in motion with a constant velocity unless acted upon by an external force”. That is, the skater will continue to coast unless he/she stops by applying brakes or he/she bumps onto someone or falls and trips due to loss of balance.
This is how physics and skating are related by Newton’s laws of motion. Next time you skate, experience it from physic’s eyes.