Natural Laws and Driving

This module discusses how natural laws and science influence driving.
Experience helps in understanding these influences, despite the numerous moving parts involved.

Braking Distance

Braking distance is the distance a car travels from a certain speed to a complete stop.
Factors include:
- Speed: Always a significant factor.
- Tires: The connection to the road; poor condition increases braking distance.
- Brakes: Bad brakes increase braking distance.
- Road Surface: Different surfaces offer varying levels of friction. Smooth surfaces like parking garages reduce grip.
- Weight: Heavier cars require more energy to slow down, necessitating better tires and brakes.
Consider these factors before needing to stop, especially on less grippy surfaces like wet roads.
When the car is loaded with weight, it will take it longer to slow down.

Road Conditions

Road repair materials, like tar, can affect grip if extensively used.
Smooth lanes worn by tires can reduce grip, especially in wet conditions. Shift your position slightly to gain more grip from the road's surface, but be cautious of surroundings.

Hills

Downhill driving increases stopping distance due to gravity; drivers may also lose track of speed.
Brake a bit earlier when slowing down or stopping on a hill.

Vision and Tires

Get eyes checked every one to two years.
Check tire tread by looking for wear bars. If the bars are close to the surface this indicates it's time for new tires.
Use the penny test if you don't have a tread gauge:
- Insert a penny upside down into the tread groove.
- If you see all of Lincoln's head, your tire is worn out.

Three-Second Rule

Maintain a three-second following distance in good driving conditions.
Choose a fixed object and count "one one thousand, two one thousand, three one thousand" after the car in front passes it. If you reach the object before finishing the count, you're too close.

Braking Distance Chart

Understand the distances, noting it's not a linear progression.
Increased speeds require more than proportionally longer braking distances due to reaction time and braking mechanics.
At faster speeds sometimes it's harder to get to a lower speed.

Horn Use

Use the horn to warn others of potential problems and avoid accidents.
Friendly horn usage is acceptable.
Do not use the horn to express anger which could lead to road rage.

Safe Driving at Night

At night, tiredness can be a greater risk.
In unfamiliar areas, increase following distance and reduce speed.
Interior and dashboard lights can reflect off windows, impairing visibility. Dim these lights to improve night vision by allowing pupils to dilate.
Use the rearview mirror's night position to deflect bright headlights.

Friction and Skidding

Grip is related to friction.
Friction is the degree to which two surfaces stick together.
A skid occurs when tires lose friction with the road, causing the car to slide.
Skidding is caused by a lack of grip or traction.
Causes are:
- Tire condition and pressure: Imbalances can cause skidding during sudden stops or starts.
- Quick directional changes lead to skidding. Two types:
  - Understeering
  - Oversteering
- Weather: Reduces tire grip and causes skidding.
- Excessive speed, acceleration, or braking.

Types of Skids

Weather is a common factor, but should not serve as an excuse.
Understeer Skid: Front tires lose grip; car continues straight despite steering input. To recover, release the brake and steer in the direction of the skid until grip is regained, then gently slow down.
Oversteer Skid: Rear tires lose grip; the back of the car slides out. Recover by releasing the brake and steering into the skid. As the car straightens, correct the steering to avoid skidding in the opposite direction.

Understeer Video Explanation

Understeer occurs when the vehicle is asked to do more turning than there is traction available to do so.
Three steps:
- Identify that you're in an understeer - wheels aren't turning and the car is not turning as much as you want it to.
- Unwind the wheel.
- Most importantly, stay off that brake.

Ice Road Safety Video Breakdown

Oversteer Slides: Often happen at high speeds.
Three points to remember:
- Don't use your brakes; braking will make it worse.
- Turn into the slide, meaning same direction that the rear of the vehicle is sliding.
- Don't panic and don't overcorrect, this will spin the car out.
Braking should be avoided as it worsens the slide by causing total spinout.
One of the reasons a driver was able to execute it was because the road was salted at that location.
Hitting the brakes initiates a slide, as shown by the brake lights on a pickup truck.
Slowing down below $45$ mph when icy conditions are in place will ensure the best outcome and avoiding the slide altogether

Road Design and Awareness

Banked curves increase downforce and traction.
Adverse banking decreases traction.
Road crown is the curve of the road, and allows for water to flow off the road.

Miscellaneous

Sign up for the road test as soon as you get your permit.
Aim means don't look right down in front of the car, but look down the road to see what is coming.
Getting the big picture means not just focusing on the road, but on the whole thing - looking for side streets, pedestrians, traffic signs, etc.
The Smith system, keep your eyes moving, otherwise your brain will block out details.
You need to be done with all DE required thirty days before birth test so the paperwork can get through.
Leave yourself an out, meaning have a safety buffer, and extra space.
Normal following distance in good conditions is three seconds.
The Smith system makes sure they see you. This includes things like having your headlights on all the time.

Physics of Car Crashes

The video explores the physics of car crashes, car safety, and how cars are designed.
Focus on the concepts, not memorizing formulas.
Inertia is the resistance to change in motion. Newton's first law (law of inertia): a body in motion stays in motion unless acted upon by an external force.
Occupants keep moving at the vehicle's speed until an external force stops them.
Seatbelts help occupants slow down with the vehicle, utilizing the crumple zones to absorb crash forces.
Newton's Second Law: $F = ma$ , where:
- $F$ = force
- $m$ = mass
- $a$ = acceleration
Momentum is inertia in motion calculated as: $p = mv$ . Has a directional property; therefore is a vector quantity
Impulse affects momentum: Impulse = Force \/ Time. Applying a smaller force over a longer time reduces the impact.
A g is a unit of deceleration. Higher g-forces during rapid deceleration can cause injury.
Extending the time of impact through airbags and crumple zones minimizes injury.
In collisions, the law of conservation of momentum applies: total momentum remains constant.
Collisions between vehicles of different masses affect occupant safety; lighter cars offer less protection.
Kinetic energy (KE) is related to motion and is calculated as: $KE = (1/2) * m * v^2$ . Speed is critical because kinetic energy is proportional to the square of velocity.
Managing kinetic energy during a crash is crucial for safety.

Crashworthiness

Crashworthiness refers to the protection a car offers during a crash, involving structural design and restraint systems.
The occupant compartment should remain intact, with damage confined to the front end.
Crumple zones in the front end should buckle to slow down the occupant compartment, reducing the force of impact.
Side impact crashes require additional safety measures like side airbags and inflatable head protection due to limited crush space.

Speed and Safety

The energy in a collision is disproportionately affected by high speeds due to the velocity squared relationship.
A crash at $40$ mph is four times as bad as one at $20$ mph.
Speed is a critical factor in fatal crashes.
Driving under the influence with speed can be lethal