# How Much Do You Know About the Physics of Driving?

4 min
Image: Getty Images via Donald Ian Smith

If you think physics is only for people like Albert Einstein or Stephen Hawking, think again; no matter how much you hate math or think that science just isn't your thing, the laws of physics are acting on your every single day as you go about your normal routine.

Physics, a branch of science that deals with matter, energy, and motion, has a huge impact on normal activities. The laws of motion are governing your activity when your standing still, walking or even driving. Understanding the basics of how physics works will not only expand your mind; it can actually make you a better driver, and may even keep you safer on the road.

Ever wondered about why you always hear about the two-second rule when it comes to following distance? Believe it or not, it's simple physics; just like acceleration, speed, braking and that skid that happens when you take a turn too fast.

Think you know how the field of physics is related to driving? Take our quiz to test your knowledge of the physics rules of the road!

If you get a speeding ticket, it most likely means that the police noticed your...
average velocity
instantaneous velocity
deceleration
mass

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.

Stating that your car goes from 0 to 60 in 3 seconds is an example of what?
force
mass
acceleration
G-forces

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.

What physics term describes why you get whiplash if your stationary car is hit from behind?
newton
inertia
pascal
vector

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.

Trucks take longer to stop than cars because they have more...
velocity
mass
acceleration
deceleration

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.

Are race car drivers more likely to experience G forces if they speed up or slow down?
speed up
slow down
race car drivers never experience G-forces
G-forces only apply in outer space

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.

Which accelerates faster, given identical conditions, a Jeep or a Porsche?
Jeep
Porsche
They accelerate at the same rate.
Neither of these can accelerate.

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.

What happens to your car on the highway if you take your foot off the gas?
It will speed up.
It will slow down but never stop.
It will slow and eventually stop.
Nothing will happen.

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.

What force causes your body to lean to one side when driving around a curve?
Newtonian force
Friction
Vector
Centrifugal force

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.

What force causes your wheels to rotate on their axes?
torque
mass
deceleration
Pascalian 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.

What force causes your car to go faster when you're traveling down a hill?
gravity
acceleration
friction
banking

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.

What is the term for the friction between your tires and the road?
inertia
traction
velocity
gravity

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.

Which of these laws helps explain why your car is pretty easy to steer in a straight line on the highway?
law of inertia
law of averages
law of force
law of velocity

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.

How much does stopping distance increase when you increase your speed from 10 to 20 mph?
It stays the same.
2 times
3 times
4 times

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.

Momentum is a factor of mass and...
velocity
gravity
friction
torque

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.

Why does a car get damaged in a crash?
It absorbs gravity.
It absorbs momentum.
It absorbs acceleration.
It absorbs velocity.

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.

Which of these factors reduces tire traction?
overinflation
underinflation
bald tires
all of the above

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.

Which of these increases traction?
sand
ice
snow
rain

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

What are banked roads meant to counteract?
centrifugal force
Newtonian force
Pascalian force
acceleration force

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.

If you know you're about to crash, which of these is it best to aim for?
a tree
a metal light pole
sand barrels
concrete jersey wall

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.

What happens to loose objects in the back seat when you slam on the brakes?
They fly forward.
They remain at rest.
They are thrown towards the rear window.

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.

What do the sensors on anti-lock brakes detect?
gravity
deceleration
mass
plutonium

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.

55 miles per hour is an example of...
acceleration
mass
energy
velocity

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.

How far do you travel in one second at 55 mph?
10 feet
20 feet
40 feet
80 feet

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!

What is the average stopping distance for a car going 55 mph?
20 feet
80 feet
360 feet
1,000 feet

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.

What happens to stopping distance when speed doubles?
It is reduced.
It is the same.
It doubles.

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.

Which of these increases your stopping distance?
going down a hill
driving an oversized vehicle
all of the above

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.

Which of these types of accidents has the highest impact force?
t-bone crashes
being rear-ended
side swiping

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.

T-bone crashes typically cause less damage than head-on collisions.
True
False

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.

Why is a rear-impact accident the least damaging type of car accident on average?
The car in front can move forward.
The car in front is stationary.
The back car can reverse.
They are extremely rare.

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.

Velocity is exactly the same as speed.
true
false

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.

What happens if you don't wear a seatbelt and you crash?
nothing
Your body goes toward the backseat.
You will move toward the roof of the car.
You move toward the windshield.

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.

What do physicists call the effect of air on a car?
wind
drag
friction
velocity

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

Why do crumple zones reduce damage and injury?
They increase velocity.
They increase inertia.
They decrease mass.
They decrease deceleration.

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.

Which of these can improve acceleration?
more powerful engine
swapping aluminum panels for steel
moving the seat further back

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.

What will happen to your car if you carry a lot of heavy stuff in the trunk?
It will go faster.