Have you ever wondered about something interesting like this? It turns out the answer is closely related to various physics theories. Trains require less friction, which is why they have metal wheels, while cars need high friction and thus require rubber tires.
There are all kinds of transportation around us, featuring various forms and elements. Different modes of transport utilize different technologies to operate efficiently.
While cars drive on roads using rubber tires, trains and high-speed trains run on tracks with metal wheels instead of rubber.
So why do we use different types of wheels for different modes of transportation? What are the key factors that influence the choice of wheels?
Train Wheel.
Before discussing the reasons, let’s identify some factors that must be considered when deciding on the type of wheel to use. Remember that many factors play a role, but here are the main ones:
Friction is the most important factor in determining what type of wheels a vehicle needs. Friction is a form of force. Typically, friction occurs when the surface of one object comes in contact with the surface of another. Each object exerts a force on the surface of the other in the opposite direction of the other’s movement.
We know that the lower the friction, meaning the smoother the contact surfaces, the faster they can move past one another.
Different vehicles imply they will move at different speeds. The speed of something in motion and the duration it maintains that speed play a decisive role in the type of wheel that will be used.
Depending on the terrain a vehicle traverses, different types of wheels will be needed to suit it.
Trains travel long distances at high speeds while carrying a significant amount of cargo and passengers. Therefore, choosing the right wheels is not a simple task.
First, friction must be minimized for train wheels. A train moves on tracks that are completely uniform and smooth. As there are no bumps or holes on the route, the train’s goal is to maintain high speeds.
Trains can maintain high speeds if there is very little friction between the wheels and the tracks. This is thanks to wheels made of smooth metal. Both the tracks and wheels are made of metal, polished against each other, which helps reduce friction. In fact, it has been found that friction is reduced by 85% to 99% when steel wheels are used on steel tracks.
Trains do not need to stop abruptly because they carry a lot of weight and momentum. For this reason, trains do not require wheels that generate friction. That is why metal wheels are chosen to reduce friction and maintain speed for trains.
In contrast, rubber wheels require a very high amount of energy to move. Most of the energy and force generated by a car’s engine goes towards spinning the rubber wheels.
Now, if train wheels were made of rubber, the engine would need an enormous amount of energy/force to move the train due to its heavy weight. Friction also increases as the weight of an object increases, leading to more friction from rubber tires.
Unlike trains that run exclusively on tracks, cars or any vehicles must travel on roads. Cars often have to navigate various terrains, from pothole-filled roads and muddy paths to smooth asphalt.
Uneven terrain is not an unusual challenge for vehicles like cars. All of these situations require the vehicle to grip the surface it is moving on. This grip can only be achieved if there is sufficient friction between the wheels and the terrain. That is why rubber tires meet the criteria for generating and maintaining friction with the terrain.
Rubber Tires Meet the Criteria for Generating and Maintaining Friction with the Terrain.
The roads and terrains that vehicles traverse also continuously wear down tires. However, frequently replacing metal wheels would be very costly. Rubber tires are relatively cheap to replace and last longer under such harsh conditions.
Cars also need to brake and stop more frequently than trains, so equipping them with rubber tires helps address this issue.
Since cars only need to maintain a certain speed and are not as heavy as trains, rubber tires do not hinder acceleration and do not waste the engine’s energy like they would for trains.
Many factors influence why vehicles use certain types of wheels, but the most important remains friction.
Because trains need to move quickly continuously with large masses, they require less friction, making the use of metal wheels completely rational. Meanwhile, cars must traverse uneven terrains and roads that require high friction, making the use of rubber tires logical.
