Physics In Transportation

Flying an Aeroplane

For an aeroplane to fly, these four different forces – weight, lift, drag and thrust, need to have the right balance. These forces fall within the study of aerodynamics within Physics. Aerodynamics is simply the way air moves around things. Hence anything (e.g.: planes, birds, kites, cars) that moves through air reacts to aerodynamics.

Everything on earth has weight which comes from gravity pulling down on objects. Lift is the push that lets something move up, a force that is opposite of weight. Drag is a force that tries to slow something down by making it hard for an object to move. The more air that hits a surface, the more drag it makes. Thrust is the force that is opposite of drag, the push that moves something forward.

Airplane wings are an important component of lift due to the difference in air pressure on the top surface as compared to the under surface as a plane fly. This difference causes the airplane to go up and is caused by the shape of an airplane’s wings as they are curved on top and flatter on the bottom.

The Bernoulli principle, named after the Swiss scientist Daniel Bernoulli, is a foundational principle of aerodynamics where he discovered pressure of fluids decreases as velocity increases. Alongside Newton’s three laws of motion, these principles formed the concept behind the flying of planes.

Driving a Car

Cars rely on the laws of Physics to operate. Without natural forces like inertia, gravity, friction and energy, it would not be possible to start, move, stop or change the direction of the car. The design of the car is also able to influence the interaction of these forces with the car.

• Gravitational Force

Gravity pulls the car towards the centre of the earth. The downward pull of gravity will affect the car’s speed when one is driving or parking on a slope. If you are driving uphill, the car would slow down; if you are driving downhill, it will speed up.

• Energy and potential energy

The amount of kinetic energy your car has will affect how easy it is to slow down or stop. This affects braking distance and the force of impact in collisions, where these phenomena are based on Newton’s three laws of motion related to inertia, the force of a moving object and the law of action and reaction.

• Centrifugal and Centripetal Forces

These forces work in opposition to each other and affect objects traveling on a curved path, like how a car behaves along a curved road. When driving on a curved road, your car will always be acted on by both of these forces. Striving a balance between these two forces help to avoid understeering or oversteering.

• Friction

Friction is the resistance between any two contacting surfaces as they slide against each other, also known as traction for the friction between car tires and the road. The traction force must be high for the car to move safely and for the driver to steer effectively. Friction is also needed during braking. To slow down or stop, the brakes must absorb the vehicle’s kinetic energy.

Maglev Trains

Maglev (abbreviation for magnetic levitation) trains are high speed trains powered by magnetic forces. This concept was birthed by James Powell when he got stuck in a traffic jam, dreaming of superconducting magnets to levitate a train car.  Superconducting magnets are electromagnets that are cooled to extreme temperatures during use (e.g.: -233 degree Celsius), which dramatically increases the power of the magnetic field (up to 10 times stronger than ordinary electromagnets).

In Maglev, superconducting magnets suspend a train car above a guideway. Like ordinary magnets, these magnets repel one another when like poles face each other. These magnetic fields interact with simple metallic loops set into the walls of the Maglev guideway. Both magnetic attraction and repulsion are used to move the train car along the guideway.

A big benefit of the Maglev train is safety. These trains are “driven” by the guideway with no drivers. No two trains on the same route can catch up and crash as they are being powered to move at the same speed. Train derailments are almost impossible too as the further a Maglev train gets from its normal position between the guideway walls, the stronger the magnetic force pushing it back into place becomes.

(Note: Not all bullet trains are Maglev trains as some bullet trains have wheels but Maglev trains have no wheels.)