Module 3 - Forces and Motion (Linear Motion) Flashcards
When are the equation of motion applicable
- Negligible Air resistance
- Linear Acceleration
what does the mneumonic suvat stand for
s - displacement
u - initial velocity
v - final velocity
a - acceleration
t - time
What is the suvat equation with the abscence of displacement
v = u + at
What is the suvat equation with the abscence of acceleration
s = 1/2(u+v)t
What is the suvat equation with the abscence of final velocity
s = ut + 1/2 at^2
What is the suvat equation with the abscence of time
v^s = u^2 + 2as
What is meant by the term Stopping Distance
The distance travelled by a vehicle from the moment a person reacts to when the vehicle stops
What is meant by the term Thinking Distance
The distance travelled by the car from when the person reacts to stop to when they press the brakes
What is meant by the term braking distance
The distance travelled by the vehicle after the brakes are applied to when the vehicles stops
How is the stopping distance calculated
Stopping distance = thinking distance + braking distance
What is the typical range of reaction time
0.4s - 0.8s
Derive proportionality between thinking distance and speed
- because reaction speed has a a set range it can be called a constant.
- this means that the equation d = s x t can be called as d = k s showing that thinking distance is directly proportional to the speed of the vehicle.
Derive the proportionality between braking distance and speed
- 0.5mv^2 = F x d because the work done by the brakes until the vehicle stops is equal to the intial kinetic energy store of the vehicle
Constants: 0.5, m, F - k1 x v^2 = k2 d
- v^2 = k d showing that the braking distance is directly proportinal to the square of the vehicle velocity
What are factors affecting Stopping distance
- condition of the brakes (F)
- mass of the vehicle
- the velocity of the vehicle
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