Arvin is driving along and suddenly someone passes him. Arvin feels like he cant let them get away with that, so he steps on the gas and tries to catch up. And then, all of a sudden, his helmet flies off! Uhh, I can feel his embarrassment.
Have you experienced what Arvin has? If you have, I know the person to blame, his name is Aerodynamic. Basically, aerodynamic is study of air movement around solid object. When solid object get through the air, it messed up the air flow around it by moving air molecules aside which can effect the motion of the object.
The principles of aerodynamics are thrust, drag, weight, and lift. Thrust is the force that moves something forward, while drag is the force that caused by air which slowing something down. An object will move forward if it has more thrust than drag. Similarly, weight is the force that pulls an object downwards due to gravity, while lift is the upward force that opposes weight and helps to keep an object move up.
Back to Arvin’s embarrassing moment, his pink headgear gets a principle of thrust by his motorcycle that moving him forward and principle of drag as it get through the air. In other words, Arvin’s helmet gets principle of thrust and drag at the same time. As I mentioned earlier, an object can move forward if it has more thrust than drag. Conversely, it will slow down or even move to the opposite direction if it has more drag than thrust (just like Arvin’s helmet).
Lets jump to technical explanation, get ready to have your brain scrambled!
The more surface area the object has, the more drag it generates. So, the shape of an object is the key to measuring the force of drag. It can be concluded that the poor dude helmet had a poor shape which caused the messed up air flow and generates more drag.
This case would make more sense if Arvin were using a non-fitting helmet. A non-fitting helmet can create a high pressure air that is trapped in the space between the helmet and the Arvin’s head. The pressure difference between the surface of the helmet and the inner space of the helmet can create additional drag force which can cause the helmet lift off from Arvin’s head.
So, its correlate to the design of the helmet. A proper design will minimize the drag and create a smooth air flow around the helmet. Now check your helmet for sure, chuck it to the trash if it has no proper design, that cheaper headgear make you look ugly too.