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# Physics Project

By Shierlyne Delena, Brian Lam, Justin Mitchell, Devin Hand, Virgil Pacis
by

## Ashley jl

on 25 January 2014

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#### Transcript of Physics Project

Friction on curves
INTERSECTION
Stopping Distance
Friction
Speed
When a car is traveling at a high speed, a driver has less time to identify hazards and react to what is happening around them. It takes vehicles further to stop from higher speeds, and if there is a crash, the injuries will be more severe.

When the Road is the dry the Friction is greater between the road the tire.
When the road is slippery or wet the friction of the car is reduce and it will take longer to come to a completely stop because the component is between the road and the tire causing the car to skid on the road.
Physics Project

By:
Shierlyne Delena
Virgil Pacis
Brian Lam
Justin Mitchell
Devin Hand
Stopping Distance Formula
Where V is the velocity
u is friction coefficient,
g is acceleration due to gravity.

Friction is the resistance force made by rubbing off two objects.
The process of stopping your car has two main components: reaction and braking
Stopping distance formula is used to find the stopping distance d, velocity v coefficient of friction µ and speed of the given body v if some of the quantities among these are known.

Reaction Time
Following Distance
Maintaining a safe following distance gives you sufficient time to react to emergency situations. The safe following distance will vary with your alertness, the size, condition and speed of your vehicle, the road surface and the weather conditions.
If the road is wet, icy, curvy, or visibility is limited, then you need to increase your following distance.
When the road is slick, you need to have more room to stop.
Video
The gap between your vehicle and the vehicle in front.
Stopping Distance
Friction on curves
Following Distances
Intersection

d = -Vo2/(2a)

d = V2/(2g(f + G))
Stopping Distance = Thinking Time + Braking Distance
Thinking distance is the distance that the car travels after the driver has seen the danger and before the brakes are applied or the Reaction Time.
The braking distance. is the time it takes for the car to stop once braking has started.
the faster the vehicle is travelling the greater the actual braking distance is compared to the thinking distance
Distractions
Worn brakes, extra weight, bad tires.
The weather condition (wet, icy - anything that reduces friction)
grooming

Thinking distance is affected by:
The driver's reaction time.
Your reaction time can be affected by:
distractions in the car,
distractions outside the car (not just distractions - sunlight reflected into eyes can affect the time interval between the braking occurrence happening and the driver reacting to it),
alcohol,
medication,
age - your thinking processes slow as you approach old oge.
The equation used to calculate the braking distance
Vf
= Final velocity
V/Vi
= Initial velocity
a,g
= Acceleration rate/gravity
d
= Distance traversed during acceleration
G
f
= Coefficient of friction between the tires and the roadway

The perception time can be as long as ¼ to ½ a second.
Reation Time depend on the level of alertness of the driver and the condition of the road.
-the rate of change of distance with time.
**Speed is the velocity of a car.
v = s/t
Speed is directly proportional to distance when time is constant: v ∝ s (t constant)
Speed is inversely proportional to time when distance is constant: v ∝ ⅟t (s constant)
Friction is the main reason for the car to stop.
Road conditions along with tire conditions and the size of the car would effect the stopping distance.
The net force on a car traveling around a curve is the centripetal force, directed toward the center of the curve.
Level Curve
Fc = m v2 / r

Fc
=flow control
M
=motion√
V
=velocity
R
Centripetal Force
For a level curve, the force of friction is the only horizontal force on a car and provides the centripetal force.
The normal force and the weight simply cancel each other.
Calculations are easier if the speed is expressed in m/s
For a level curve, the centripetal force will be supplied by the friction force between the tires and roadway.
A banked curve can supply the centripetal force by the normal force and the weight without relying on friction.
Banked Curve
If the speed of the car, v, is greater than the ideal speed for the turn, the horizontal component of the normal force will be less than the required centripetal force.The friction force will pull the car down the incline, in the general direction of the center of the turn.
If the speed of the car is less than the ideal (no friction) speed for the turn. In this case, the horizontal component of the normal force will be greater than the required centripetal force and the car will "want to" slide down the incline toward the center of the turn.
If there is a friction force present between the car's tires and the road it will oppose this relative motion and pull the car up the incline.
Speed, amount of cars around you, amount of time it took for the light to switch to yellow, friction, wetness of the pavement, and stopping distance.
3-Second Rule
The time and distance it takes for a driver to stop their vehicle safely in emergency circumstances also depends on Reaction distance, Braking distance, The Stopping Distance, The 3-Second Rule, and Long Vehicles.
While watching the vehicle in front of you pass an object and then count the time (typically around 3 seconds) it takes for you to reach that object. If you’re closer than 3 seconds, then back off slightly to reach a three-second following distance. If you’re traveling at speeds over 30 mph, in heavy traffic, bad weather, or following a motorcycle, truck or bus, try to maintain a following distance of 4 seconds or more. It’s up to the driver to use their best judgment to decide when more space is needed.
Rules & Distractions
-allows for a safe following distance when the road is dry and straight.
Situations requiring a greater following distance include;
driving in wet weather, fog, snow, ice
when smoke is across the road
when following a large vehicle
when being followed by a large vehicle on dirt roads
If being followed closely by a large vehicle, increase your following distance from traffic ahead, so if you need to brake hard, you can do so more gradually, and thus avoid the unpleasant experience of being run over by the truck.
A flashing yellow light means you should drive with caution when approaching and moving through the intersection.
For a 'stale' light, begin slowing down early to keep a safe distance between you and the vehicle behind you and plan to easily stop with the front tires behind the stop bar when the light changes from green to yellow"
if you are 100 feet or less from the intersection, you have passed the “point of no return” and cannot stop safely before the intersection.
Yellow light times based on speed zones:
25 MPH -- 3.0 Seconds
30 MPH -- 3.5 Seconds
35 MPH -- 4.0 Seconds
40 MPH -- 4.5 Seconds
45 MPH -- 5.0 Seconds
50 MPH -- 5.5 Seconds
55 MPH -- 6.0 Seconds
http://auto.howstuffworks.com/car-driving-safety/6513-mythbusters-speed-camera-uncut-video.htm