what is gravity vehicle
A gravity vehicle is a car that is solely powered by the gravitational potential energy it has when it is placed on a ramp. Many science and engineering competitions, such as Science Olympiad, hold gravity vehicle as an event to learn physics concepts.
In this post, we will discuss how you should design your gravity vehicle ramp to achieve the best results.
what you should consider
Ramp Height and length
When you begin to design your gravity vehicle ramp, it is imperative to maximize the ramp height and length. Many competitions limit or restrict the the dimensions of your ramp. However, it is in your best interest to maximize the height and length specifically.
The reason to maximize the height of your gravity vehicle ramp is because the higher the center of gravity of your vehicle is, the greater the amount of potential energy you car has. And because in a perfect world Kinetic Energy = Potential Energy, your vehicle will travel faster.
When you increase the length of your ramp, the transition from the top of the ramp to the bottom becomes a lot smoother. This is largely because a larger length for your tamp allows for an elongated transition curve, allowing for a smoother transition.
Contrary to other aspects of ramp dimensions, ramp width can be adjusted in many different ways.
If you want your gravity vehicle ramp to be more portable , then you only need to build your ramp to be the width of you vehicle plus an extra 5-10 cm.
Trying to make your ramp width closer to the maximum limit is overly excessive and can make the portability of your ramp very poor. The only reason to justify the maximum ramp width is that your vehicle does not travel straight down the ramp.
When designing the curve of your ramp, it is important to know the entire length of your vehicle. This is because you want your transition curve to begin where the front wheels of the car will be placed onto the curve when the vehicle is in the ready-to-run configuration.
A brachistochrone curve is a curve that has the fastest path to reach the bottom of the ramp. So then a brachistochrone curve is the best way to design a ramp, right?
Yes, a brachistochrone curve is the fastest way to get the vehicle down the ramp but the amount of speed that your vehicle could possibly have is mainly determined by the gravitational potential energy of your vehicle. In other words, the speed of your vehicle is not effected by the ramp curve but only by ramp height.
While the launching mechanism may not be a determining factor for vehicle speed, it does, however, effect your consistency. When designing the launching mechanism on your ramp, you want to reduce the contact between the mechanism and the vehicle, which, in turn, will reduce the friction between them.
Look forward to a future post outlining how to build the best launching mechanism for your ramp.