How Much Do You Know About the Physics of Driving?

It doesn't matter if you virtually always drive below 55; all that cop cares about when he's pointing his radar gun in your direction is your instantaneous velocity. That's how fast you are traveling at one particular moment, not your speed over time.

In physics, acceleration is equal to velocity over time. That means that when you brag about how fast your car can go from 0 to 60, you're talking up your car's velocity.

You've heard of Newton's laws of motion, right? Well, if you're sitting in your car at a red light, and someone hits you from behind, an object at rest, that's your car, is no longer at rest, but suddenly in motion. This effect, where the vehicle moves forward while your head is trying to remain at rest is an example of inertia.

The reason you want to give trucks more time to stop than you would a car is a simple matter of physics. Those trucks take longer to stop because they have a whole lot more mass than a car.

Force is calculated by multiplying mass times acceleration. By speeding up, drivers increase acceleration, which in turn increases force. That's why a driver at the Indy 500 going around a bend at 230 mph will experience several seconds of 3 G's.

Acceleration is calculated by looking at the velocity over time. A Porsche is designed to maximize velocity, while a Jeep is built for other things, like off-roading. That ability to maximize velocity explains why a Porsche accelerates more rapidly than a Jeep.

If you take your foot off the gas pedal, the only forces working on your car are friction and air drag. Eventually, those two forces will combine to slow, then stop your vehicle.

You ever noticed that when you go around a sharp curve in your car, you body automatically leans towards the outer edge of the curve? That's physics - it's known as centrifugal force.

Torque is a force that comes from your engine. This force, or energy, causes the wheels to rotate, which allows them to overcome the friction from the road so that the car can move.

Gravity is one of the most basic forces in all of physics. It's what makes your car roll a little faster when traveling downhill, and what slows the car down when traveling up a hill.

Traction is a term that describes how much friction exists between your tires and the road. It can be affected by everything from road conditions, to the condition of your tires or what material the road is built from.

The law of inertia explains that an object in motion will remain in motion unless acted on by an outside force. That helps explain why it's fairly easy to keep your car on a straight path as you cruise down the highway.

In physics, kinetic energy is equal to one-half of mass times speed-squared. That's why stopping distance is four times longer when increasing from 10 to 20 mph, or 25 times longer when going from 10 to 50 mph.

In physics, momentum is calculated by multiplying mass times velocity. That means that the faster you drive, the more momentum your vehicle has. This is why a high-speed crash is usually more deadly than a slow-speed one, all other things being equal.

When a vehicle comes to a sudden stop due to impact, the laws of physics state that all that momentum has to go somewhere. Damage to a crashed vehicle occurs because the car has absorbed the momentum upon impact.

All three of these factors, including old, bald tires or overinflation/underinflation can reduce the friction between your car and the road. This is bad news, as it can mean less traction, and thus, less control over your vehicle.

Ice, snow, and rain all reduce traction. Sand or dirt can increase friction to improve traction.

Thanks to centrifugal force, your body naturally leans towards the outside of the circle as you drive around a curve. Banking, or angling the road in these areas helps to reduce this effect.

Sometimes you know your vehicle is heading off the road, and you might have a split second to choose your path of travel. In this case, avoid solid objects like trees and poles and head for things like bushes, snow banks or sand barrels. All of these things could reduce your impact by slowing it down.

A basic law of physics states that an object in motion will stay in motion - that's inertia. It's also why any loose objects in your backseat are going to fly forward if you have to slam on your brakes suddenly.

Those cutting-edge sensors used in anti-lock brake systems are looking for a sudden deceleration in one of your tires. By spotting this deceleration, the system can adjust the braking pressure to keep wheels from locking up.

Velocity tells you the distance you travel over a specified period of time. That means those 55 mph speed signs are pointing out maximum velocity permitted by law.

If you are traveling at 55 mph, your car will travel 80 feet in just one second. That's about one-fourth the length of a football field!

From the time you apply your brakes while traveling at 55 mph, your car will travel around 360 feet, the length of a football field, before coming to a complete stop. That's why it's so important to look ahead for obstacles as you drive.

Doubling your speed while driving means your car will take four times as long to stop. That means that you should leave at least four times the following distance between yourself and the vehicle ahead of you if the speed limit has doubled.

The two-second rule doesn't always work. That's because a whole lot of factors can cause your car to take longer to stop, including traveling down a hill, driving an heavier or larger vehicle, or driving on wet roads.

Two vehicles crashing head on has the greatest impact force of all crash types. That's because all that momentum from both vehicles has nowhere else to go but to the vehicles themselves.

The explanation behind why a T-bone crash, while still terrible, is less dangerous than a head-on collision comes down to physics. In a T-bone collision, the car that has been hit from the side can still move forward in some way, meaning that not all of the impact or momentum of the crash has to be absorbed 100 percent by the cars themselves.

In a rear-impact collision, the front car is often pushed forward. This helps to dissipate some of the momentum and reduce the amount of damage.

While beginner physics often simplifies this concept, speed and velocity aren't the same. Speed is how fast the car travels, while velocity is how fast the car travels in a particular direction.

You know that whole law of motion that Newton came up with? Well, it applies to driving, too. If you neglect to wear your seatbelt, and the car comes to a sudden stop, your body will keep moving forward, sending you toward or through the windshield.

The effects of air on driving are known as drag. Friction usually refers to the traction between the wheels and the road.

When a car decelerates suddenly, all that momentum and energy has to go somewhere. Crumple zones slow this deceleration to reduce overall damage and injury risk.

Acceleration is equal to velocity over time. Generally, anything that increases velocity, like lightening the vehicle or putting in a bigger, more powerful engine, will help boost velocity.

Anything that increases the weight of a car makes the engine work harder to overcome the forces of friction and drag to get the car rolling. Carting heavy stuff around in your trunk makes your engine work harder than it has to, which reduces fuel efficiency.