Kinematics Flashcards
Speed, Velocity, Distance, Displacement, Acceleration
What is Distance?
Total length covered between 2 points (Scalar)
What is Displacement?
Straight line distance in a specific direction between an object and a specific point/starting point (Vector)
SI unit for Displacement and Distance?
metres (m)
What is Speed?
Rate of change of Distance (Speed= d/t) (Scalar)
What is Velocity
Rate of change of Displacement (Velocity= displacement/time) (Vector)
SI unit for Speed and Velocity?
m/s or ms^-1
What is average speed?
Total d/Total t
What happens when the speed is 0
The object is at rest/stationary/does not move
What is Acceleration
Rate of change of velocity
(change in velocity/time taken OR a= v-u/t) (Vector)
SI unit of acceleration?
m/s^2
What is Deceleration
An object moving at decreasing velocity OR negative acceleration
Does negative acceleration ALWAYS = to Deceleration?
No, negative acceleration can be acceleration in a negative direction
How to read a Distance-time graph?
A non-decreasing graph, regardless of whether object changes direction.
Gradient of distance-time graph at any point=Speed
How to read a Speed-time graph?
A non-negative graph, regardless of whether an object changes direction. (Speed can NEVER be NEGATIVE)
When speed=0 object is at rest
When speed>0 object is moving
Gradient of speed-time graph at any point=Acceleration
Area under speed-time graph=Distance travelled
How to read a displacement-time graph?
Can decrease, dependent on whether an object changes direction. (Can be positive or negative)
Gradient of displacement time graph=Velocity
How to read a velocity-time graph?
Can be negative or positive, dependent on whether an object changes direction.
Gradient of velocity time graph=Acceleration/Deceleration
Positive gradient=Acceleration
Negative gradient=Deceleration
Area under velocity-time graph=Distance travelled
How does terminal velocity/free-fall work
When an object is released from rest, initial velocity is 0 and no air resistance is acting on it
However when an object falls, the air resistance will increase which causes the resultant force to decrease and the acceleration to decrease
When the air resistance is = to the weight of the object, resultant force will be 0 and the object has reached terminal velocity/is in free-fall
