P3b Flashcards
(14 cards)
What do you need to know to interpret a speed-time graph?
Gradient = acceleration
Flat sections = steady speed
Uphill straight sections, positive gradient, are accelerating.
Downhill straight sections, negative gradient, are decelerating.
The steeper the gradient, the greater the acceleration or deceleration.
A curve means non-uniform (changing) acceleration or deceleration.
How do you work out the distance from a speed-time graph?
Work out the whole area under that part of the graph.
How do you calculate acceleration from a speed-time graph?
Gradient = vertical/horizontal
What is acceleration?
How quickly the speed is changing.
How can you recognise an acceleration or deceleration?
Speeding up involves a positive acceleration. Slowing down involves a deceleration - a negative acceleration.
What does a greater change in speed in a given time result in?
Higher acceleration.
What is acceleration measured in?
m/s squared
What is the equation for acceleration?
acceleration = change in speed/time taken
What can acceleration involve?
A change in direction, with or without speed.
A change in speed.
What is the formula for finding the final speed or starting speed?
final speed = (acceleration x time) + starting speed
initial speed = (acceleration x time) + ending speed
What is velocity?
Velocity describes both the speed and direction of an object. e.g. velocity = 30mph due north.
What is the importance of direction when describing the velocity of an object?
You can have negative velocities. If a car travelling at 20m/s then turns around to go in the opposite direction, the speed is still 20m/s but the velocity becomes -20m/s.
What will the velocities be for two objects moving in opposite directions at the same speed?
The speed will be the same but with different signs.
How do you calculate relative velocity?
If two objects are moving parallel to each other, their relative velocity is the difference in their velocities.
e.g. two cars travelling at speeds of 30m/s in opposite directions have a relative velocity of 60m/s - because the difference between their velocities (30 and -30) is 60.
