Topic 9 - Distance, Speed and Acceleration Flashcards
What is the equation for average speed?
Total distance/total time
What is a scalar quantity?
Only has a magnitude, no direction.
What is a vector quantity?
Has a magnitude and a direction
What kind of quantity is speed?
Scalar
What kind of quantity is velocity?
Vector
What is distance?
How far an object moves
What kind of quantity is distance?
Scalar
What is displacement?
The distance an object moves in a straight line from a starting point to a finishing point.
What kind of quantity is displacement?
Vector
What is the equation for acceleration?
Change in velocity/time taken
What is acceleration measured in?
m/s2
Key Equation 1
Distance = (initial speed x time) + ½ (acceleration x time squared)
x = ut + ½at2
Key Equation 2
Distance = ½ (initial speed + final speed) × time
x = ½ (u + v) t
Key Equation 3
(Final speed)2 – (initial speed)2 = 2 × acceleration × distance.
v2 - u2 = 2ax
Key Equation 4
Final speed = initial speed + (acceleration x time).
v = u + at
What does a distance-time graph have on the y-axis?
Distance
What does a distance-time graph have on the x-axis?
Time
On a distance-time graph, what does a straight line represent?
Motion at a constant speed
On a distance-time graph, what does a horizontal line represent?
A stationary object
How is deceleration shown on a distance-time graph?
The gradient will become less steep
How is acceleration shown on a distance-time graph?
The gradient will become steeper
What does a speed-time graph have on the y-axis?
Speed
What does a speed-time graph have on the x-axis?
Time
On a speed-time graph, what does a horizontal line represent?
No acceleration
On a speed-time graph, what does a positive gradient represent?
Acceleration
On a speed-time graph, what does a negative gradient represent?
Deceleration
On a speed-time graph, what does a horizontal line on the x-axis represent?
A stationary object
On a speed-time graph, what does a curved line represent?
An object is accelerating or decelerating at a rate that is not constant.
How do you find the distance travelled by an object using a speed-time graph?
Calculate the area under the graph
What is the area of a triangle?
1/2 x base x height
What is the area of a rectangle?
Base x height
What is the area of a trapezium?
1/2(a+b)h
What is stopping distance?
The distance it takes a car to stop in an emergency
How can the stopping distance be calculated?
Thinking distance + braking distance
What is reaction time?
The time it takes for a driver to react to a situation, during which the car carries on moving.
What is thinking distance?
The distance travelled between when the driver realises they need to brake and when they apply the brakes.
What is the braking distance?
The distance the car travels between the driver applying the brakes and the car stopping.
What are the factors affecting thinking distance?
Tiredness, distractions, drugs/alcohol
How does tiredness affect the thinking distance?
Tired drivers will react more slowly in an emergency, stopping distance is larger.
How do distractions affect the thinking distance?
Distractions will cause a driver to react more slowly in an emergency e.g. mobile phones or small children, stopping distance is larger.
How do drugs and alcohol affect the thinking distance?
Drivers under the influence of drugs or alcohol will react more slowly in an emergency, stopping distance is larger.
What are the factors affecting braking distance?
Initial car speed, condition of the car, road conditions
How does initial car speed affect the braking distance?
The faster a car is travelling, the further it will travel before it comes to a stop.
How does the condition of the car affect the braking distance?
If a car’s brakes or tyres are in a poor condition, then the braking distance will increase.
How does the condition of the road affect the braking distance?
Wet or icy conditions will increase the braking distance.
