“The Physics of Driving: part 2”

In last week's blog, we looked at some of the physics of the world that apply to driving. However, there are more natural laws that apply to driving. Part 2 of this series will look at four more physics principles and how they impact driving. 

Potential and Kinetic Energy: Potential energy is energy held by an object because of its position relative to other objects or stresses within itself. A car has higher potential energy when it is at the top of a hill because as we talked about with gravity, gravity pulls objects down toward the center of objects. Your car also has potential energy in the gas in the gas tank and with the batteries. Without these sources of energy, your car would be unable to go anywhere from a position of lower gravitational potential energy to a higher one. 

Kinetic energy is the energy an object has because of its motion. The kinetic energy is defined by the equation K=12mv2 meaning the greater the mass the greater kinetic energy, but also the greater the velocity the greater the kinetic energy squared. This means that the faster and heavier your vehicle is the more energy is needed to slow you down. 

Inertia: Newton’s first law of motion states that a body at rest remains at rest or, if in motion, remains in motion at a constant velocity unless acted on by an external force. This law demonstrates inertia. While driving a car, everything in a car is moving in the speed and direction of the vehicle. This is why if you throw a ball in a car straight up it doesn’t fly backwards. The principle also demonstrates the importance of seat belts and airbags. If you are traveling at speed and come into contact with an object at rest, your vehicle in motion will feel an unbalanced force and slow down, however, you will continue to move forward. Seat belts and airbags will help lessen the impact of the sudden unbalanced force. 

Momentum: Momentum is your mass multiplied by your velocity. The relationship between driving and momentum can be looked at similarly to kinetic energy. The heavier your vehicle is and the faster you are going the more force will be required to slow you down. It also explains the phenomenon when a big truck going at relatively low speeds can crush and move a smaller vehicle.  

Centrifugal Forces: Centrifugal forces are the force you feel when driving around a curve. This is technically seen as a fictitious force in physics, but it is felt by all individuals. This force explains along with inertia why as one turns the wheel it feels like you are being pulled outward and away from where you want to go. As you increase speed or increase the sharpness of your turn you increase this force. So, when driving slow down and take turns fluidly while looking around the curve and where you want to go. This is also why being physically fit is a necessity for driving. 

Over these past two weeks, we have covered some of the natural laws related to driving. We do not want you to be actively thinking about the physics of driving all the time, but it is fun to think about at times after performing a maneuver. Understanding the physics of driving helps drivers better control their vehicles and safely travel on the roadways.