3 - Motion Flashcards
Define distance
Length of path travelled between 2 points
(Often magnitude of displacement vector)
Can be observed and measured
Define speed
Magnitude of the velocity vector
Can only be calculated
How to calculate speed
Average speed = change in distance / change in time
In theory, every speed calculation is an average speed calculation
The smaller the change in time (and associated change in distance), the more accurately the average speed calculated equates to instantaneous speed
Calculate instantaneous speed?
Estimate for instantaneous speed can be found by taking GRADIENT OF TANGENT at a point on DISTANCE-TIME graph
Exact instantaneous speed by differentiating displacement function of body wrt time - university
Define displacement
Vector that travels directly between 2 points
Magnitude of displacement vector = length of shortest path between 2 points
Define velocity
Rate of change of displacement of a body
Can only be calculated
Speed equation
Speed = distance / time
Velocity equation
Velocity = displacement / time
Calculate velocity ?
Estimate for instantaneous velocity by taking GRADIENT OF TANGENT on displacement - time graph
Exact instantaneous velocity - university.
Define acceleration
Rate of change of velocity of a body
Can only be calculated
Deceleration = negative acceleration
Acceleration equation
a = change in velocity / change in time
When does a body accelerate?
Change of:
- Speed
- Direction
- Speed & direction
Define uniform acceleration
A body undergoes uniform acceleration if SPEED CHANGES at CONSTANT rate WHILST travelling in a STRAIGHT LINE
(speed of the body changes by the same amount every second)
Define non-uniform acceleration
A body undergoes non-uniform acceleration if it’s SPEED CHANGES at VARYING RATE, and/ if it’s DIRECTION CHANGES
How to calculate non-uniform acceleration
Taking gradient on a velocity-time graph
