Safety OF CAR AND PHYSICS (HOW THINGS WORK?)

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# Safety OF CAR AND PHYSICS (HOW THINGS WORK?) - PowerPoint PPT Presentation

Seung-Jae You Sunghun Jun. Safety OF CAR AND PHYSICS (HOW THINGS WORK?). Which parts of the car protects the driver from accident?. 1. Tires ( Automobiles Tires and Friction) 2. Seatbelt ( Seatbelt and Inertia) 3. Airbag ( Airbag and Momentum &amp; Impulse)

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Presentation Transcript
Seung-Jae You

Sunghun Jun

### Safety OF CAR AND PHYSICS (HOW THINGS WORK?)

Which parts of the car protects the driver from accident?
• 1. Tires ( Automobiles Tires and Friction)
• 2. Seatbelt ( Seatbelt and Inertia)
• 3. Airbag ( Airbag and Momentum & Impulse)
• 4. Crumple Zone (Crumple zone and Newton’s Law)
Automobiles Tires & Friction
• The friction between the tires of an automobile and the road determine the maximum acceleration.
• However, more importantly, it determines the minimum stopping distance
• The nature of the friction could actually be a matter of life and death.
• As a result, more friction, more safe
Automobiles Tires & Friction
• How can we increase the friction?
• Increase the coefficient of friction
• If the surface of tire is rougher, then the friction force is larger
• When a tire contacts dry asphalt ground, the coefficient of friction increases.
• On the other hand, if the roads are wet, a tire contacts with water, the coefficient of friction decreases
• ex) hydroplaning
Automobiles Tires & Friction
• Various types of tires
• This is an all-season tire. The grooves provide a way for water to escape, increasing the coefficient of friction. The grooves are small enough to prevent the bumpy ride of the next tire
• The wide deep grooves here allow snow and mud to penetrate. But they give a noisy bumpy ride on pavement ... and if the treads get clogged with mud, the treaded tire essentially becomes a mud-covered 'slick' with a low coefficient of friction
• In extreme mud, these tractor or bush tires can transfer more force, but the mud doesn't get caught in tiny grooves, so they retain their traction
Seatbelt and Inertia
• Newton’s 1st law: an object will move with constant speed in a straight line except when acted upon by a net force
• when a driver stops the car suddenly, the driver fall forwards, because the driver’s body try to maintain its speed.
• Consequently, a seatbelt holds the driver and prevents the driver from falling forwards when the car stops
Airbag and Momentum & Impulse
• Every object has momentum.
• Momentum consists of a driver’s mass and velocity

- Momentum (p) and Impulse (FDt)

- p = mv, FΔt = mΔv

• There has to be a force in order to stop the driver’s momentum.
• The driver may hits the dashboard or windshield which also acts as a force stopping the driver but it injures them at the same time
• By the way. Airbag gives a force over time (Impulse). The more the the force acts on the driver to slow him down, the less damage caused to the driver
Crumple Zone
• It is also known as crash zone.
• It absorbs energy from a collision and reduce the force of a collision.
• Bending during a car crash increases time to halt the car.
• Newton’s first and second laws are applied to crumple zone.
Newton’s First Law
• Newton’s First Law (The law of inertia.)
• Many people are injured because of the law of inertia.
• Although the car stops, the person inside does not stop.
• An unbalance force, crumple zone, lowers the tendency of people to move forward in car crash.
Crumple Zone
• Newton’s Second Law
• The second law is expressed in equation form as F=MA. (F= force, M= mass, A=acceleration)
• A=V/T (V= velocity, T= time)
• More time means less acceleration.
• Less acceleration by increased time reduces force that applies to people inside of the car.
What new insight does this topic provide to you
• Many people think tire’s surface guarantee your safety 100%, but tire’s surface just makes you safe on the snow, water, or any other ground.
• Since car body seems easily bend, Some people think that crumple zone makes the car less protected.
• However, It is just misconception. In fact, crumple zone makes car more safe.
What new insight does this topic provide to you
• A misconception of AWD and 4WD is that they are safer.
• In fact, they help little bit in cornering and driving on snow.
• However, it has nothing to do with braking ability
• AWD and 4WD do not provide additional ability for steering
• AWD and 4WD do not provide additionalability for braking.
What new insight does this topic provide to you
• Even if the car’s safety improve, this is what happen if you drive too fast

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