# Formula One Car's Momentum

#### SpyIsCake

1. Homework Statement
Why are formula one cars(except the place where the driver sits) designed to break apart into small pieces very fast?
I believe that there is all kinds of things as aerodynamics, but my assignment talks about how the breaking apart mechanism is a safety feature
2. Homework Equations
∆p = F∆t

3. The Attempt at a Solution
I believe what it's doing is that it is increasing the impulse by increasing the time it takes for the car to travel a certain distance. I do not know how. I speculated by maybe using Newton's Third Law, but that is not right.

How can breaking apart into smaller pieces increase impulse?

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#### RUber

Homework Helper
When a piece breaks off, instead of transferring the force into the rest of the car or into the driver, the force leaves the body of the car.

#### BiGyElLoWhAt

Gold Member
What do you mean, increase impulse?

#### SpyIsCake

What do you mean, increase impulse?
Impulse is change in momentum.

It increases impulse because of how it increases the time.
When a piece breaks off, instead of transferring the force into the rest of the car or into the driver, the force leaves the body of the car.
I wrote that before, but my physics teacher says that the answer has to do with the time.

#### BiGyElLoWhAt

Gold Member
I know what an impulse is, but your statement about the impulse increasing didn't make sense to me.
Do you know the integral definition of impulse?
Also, you don't want the impulse to increase...

#### SpyIsCake

I know what an impulse is, but your statement about the impulse increasing didn't make sense to me.
Do you know the integral definition of impulse?
Also, you don't want the impulse to increase...
Product of force acting on the body and the time interval.

I believe that you want the time in the equation to increase, right? For example, when you cradle a ball, you receive the same amount of force.

That force is just in smaller amounts due to the time.

#### BiGyElLoWhAt

Gold Member
$I = \int Fdt$
Which is $Ft$ for constant force.
What's actually happening when a formula 1 car crashes?

#### SpyIsCake

$I = \int Fdt$
Which is $Ft$ for constant force.
What's actually happening when a formula 1 car crashes?
Sorry, but I haven't been studying that equation.

The equation that I learned is ∆p = F∆t

When Formula one car crashes, they break into many pieces. More than a normal car going that high speed.

This is apparently a design feature for the drivers inside the Formula 1 cars. Although the car breaks apart a lot, the driver tends to be alive.

Using momentum and impulse, I'm supposed to describe how breaking apart into smaller pieces help the driver.

#### berkeman

Mentor
The impulse equation shows that you get the same change in momentum with a smaller force applied over a longer time. Search for "crumple zone car crash" (without the quotes) to learn more about how to minimize the forces on vehicle occupants during crashes.

I don't understand the "parts fall off" part of the statement by your instructor, though. Crumple zones do not work by having parts fall off of vehicles.

#### SpyIsCake

The impulse equation shows that you get the same change in momentum with a smaller force applied over a longer time. Search for "crumple zone car crash" (without the quotes) to learn more about how to minimize the forces on vehicle occupants during crashes.

I don't understand the "parts fall off" part of the statement by your instructor, though. Crumple zones do not work by having parts fall off of vehicles.
What my instructor was saying that the because the formula one cars break off more easily, they make it more safe for the driver somehow.

For example, if a person was in a vehicle and parts of it start to fall off, how would that increase the change in time?

#### berkeman

Mentor
It wouldn't. I call BS on your instructor, or you are misunderstanding what your instructor is saying.

If it helped to reduce injury, then all production cars would come with body panels equiped with explosive bolts to blow off excess mass in an accident. Deploy the airbags and blow off the body panels. Right.

Tell your instructor that I call BS, and want him/her to discuss in class how crumple zones in vehicles save lives, and explosive body panel bolts do not. Let us know what s/he says... :-)

#### olivermsun

I think his instructor probably has the correct idea. The expendable parts of Formula One car bodies aren't made of crumple-able material, but they are made of stuff that can shatter into a million pieces. If done correctly, the shattering will absorb quite a lot of the excess kinetic energy in the event of a crash.

#### berkeman

Mentor
I think his instructor probably has the correct idea. The expendable parts of Formula One car bodies aren't made of crumple-able material, but they are made of stuff that can shatter into a million pieces. If done correctly, the shattering will absorb quite a lot of the excess kinetic energy in the event of a crash.
I suppose it's possible, but I'm having a hard time seeing why. The protective cage around the driver is probably designed with crumple zones in mind, though.

#### rcgldr

Homework Helper
Part of the reason Formula 1 cars break up into pieces because the components that break are designed to be just strong enough to deal with the normal stresses on the car, not to deal with the stresses from impacts, in order to save weight. Even minor contact, such as another cars tire contacting a front wing component will often shear off the front wing component, and sometimes the contacting tire gets cut and goes flat.

The main component in driver safety in the cars is a combination of a very solid and padded cage (sort of like a helmet for the driver's body) that surrounds the drivers body, legs, and sides of the helmet, surrounded by components that collapse instead of shearing off. A few years ago, the rules were changed to not allow the drivers feet to extend beyond the front axle, effectively increasing the size of the crumple zone. The parts that crumple - collapse reduced the peak g force involved in a collision by having a lower rate of acceleration (deceleration) over a longer period of time. The impulse - change in momentum is the same, but the time is longer so the peak forces are smaller.

For some components that do shear off, like an entire wheel assembly, there is a safety factor in that the wheel assembly can shear off without bringing the entire car to a complete stop. The tradeoff here is that the sheared off components could hit other drivers (or rarely spectators).

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"Formula One Car's Momentum"

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