Chapter 9 Natural Laws and Car Control Inertia

Chapter 9 Natural Laws and Car Control

Inertia, Momentum, and Energy of Motion • Inertia – objects that are at rest tend to stay at rest and objects in motion tend to stay in motion. You will feel this driving when braking, accelerating, and turning. • Momentum – the tendency of an object to stay in motion. Momentum is influenced by weight and speed. • Energy of Motion is called Kinetic Energy When a vehicles speed doubles – it takes 4 x the distance to stop When a vehicles speed triples – it takes 9 x the distance to stop • Gravity - the force that pulls things to Earth.

Tires and Traction • Friction – the force that keeps tires from sliding on the road. Heat is created when there is friction. • Traction - the tires grip on the road. Varies with road surfaces and conditions. • Tread - the grooved surface of the tires. Overinflated tires – too much air – tires grip in the center Underinflated tires – too little air – tires grip on the outside edges PSI – pounds per square inch – measures the amount of air pressure in tires Check PSI when you haven’t driven much because heat from driving them will raise air pressure. • Blowout - a sudden loss of air pressure.

• How tires grip and wear at different pressures.

Vehicle Balance 1. Vehicle balance is when the weight of the vehicle is distributed on the 4 tires. 2. Center of Gravity is the point around the vehicle that the weight of the vehicle is distributed equally.

Balance and Steering • Pitch - the tilting motion of a vehicle when you accelerate or brake too quickly.

Forces In Curves • When going through a curve, your vehicle wants to go straight due to inertia. 1. Sharpness in curves – the sharper the curve, the more traction you need. 2. Speed – the faster you go, the more traction you need. 3. Load – the ore weight you have, the more traction you need. 4. Shape of the road – a banked curve will help you drive safely through a curve. This is when the outside of the curve is higher than the inside. It helps to create better traction. ***Slow down before going into a curve!

Total Stopping Distance • This is from the time you see a hazard until you get stopped. The faster you are travelling, the longer it will take you to stop. Total Braking Distance • From the time you apply the brake until the time you get stopped. • Stopping distances video https: //www. youtube. com/watch? v=KGk. KDa. Yd 3 Mo

• Perception Time – the length of tie it takes for you to identify the hazard. • Perception Distance – the distance you travelled when you identify the hazard. • Reaction Time – the length of time you take to apply the brake. The average reactions time is 1. 6 seconds. At 60 mph you would travel 88 feet per second, which means you travel 124 feet before you even put your foot on the brake. A very alert driver can react in up to ¾ of a second. • Reaction Distance – distance you travel while you react. This is only while you react – your stopping distance would be more.

Force of Impact • This is how hard something gets hit – It is affected by speed, weight, and time Speed – the faster the vehicle is going, the more damage it will cause. Weight – the heavier a vehicle is, the more damage it will cause. Time between impact and stopping – the energy created has to go somewhere – Is the object that gets hit going to give way like bushes or not give way – like a concrete wall. https: //www. youtube. com/watch? v=v 9 ML 4 GA 47 Rg

Safety Belts and Other Safety Features • Active Restraints – a device the driver or passengers have to engage. Safety Belts • Passive Restraints – a device that works automatically Air Bags • Child Safety Seats – required in all states up to a specific weight and age of the child. • Crush Zones – areas around the vehicle that will crumple to protect the passengers inside the vehicle (as seen on previous slide’s video) • Energy Absorbing Bumbers • Side Impact Panels • Penetration resistant windshields – thin layer of plastic between two layers of glass – helps shattered window glass from going all over. • Head Restraints – to help with whiplash injuries

Chapter 9 Review • Page 179 – Vocab • Page 180 – discussion questions • Page 181 – multiple choice