P2.1 Motion Flashcards
Acceleration
Change in velocity / change in time
Force / mass
Measured in m/s²
IF SPEED AND/OR DIRECTION OF MOTION CHANGE, THE BODY IS ACCELERATING
Average speed
Total distance / total time
Measured in m/s
Eisplacement
Distance from a point in a particular direction
Gradient
Degree of steepness of a graph at any point (slope)
Change in y / change in x
y2 - y1 / x2 - x1
Kinetic energy
Energy associated with a kinetic store
KE=1/2mv²
KE = work
(Work = force x displacement)
Kinetic store
Energy in a kinetic store is associated with a moving object
KE = 1/2mv²
Scalar
Quantity that has magnitude (size) but no direction
Vector
Quantity that has direction as well as a magnitude (size)
Velocity
Speed in a particular direction
Vector quantity
Speed
Speed = distance / time
Scalar quantity
Uniform speed
Speed stays constant for the whole journey
Speed calculated from distance and time is a single value
Non uniform speed
Speed changes and is not the same during the journey
Speed calculated from (total) distance and (total) time is the average speed
How many metres in a mile
1609 meters
How many seconds in an hour
3600 seconds
Vectors vs Scalars
SCALARS ONLY HAVE MAGNITUDE
VECTORS HAVE BOTH A MAGNITUDE AND A DIRECTION
Speed vs Velocity
SPEED HAS ONLY MAGNITUDE
VELOCITY HAS BOTH MAGNITUDE AND DIRECTION
Distance vs Displacement
DISTANCE
Length of path travelled from A to B (size only = scalar)
DISPLACEMENT
Length of the shortest distance between 2 points
(size and direction = vector)
Why temperature is scalar
Temperature only has a size, no direction
Adding Vectors
If vectors act in the same direction, you add them
If vectors act in opposite directions, you subtract them
You can only add/subtract vectors that either…
… act up and down
OR
… act left and right
How to calculate relative velocity of body A to body B?
Difference between the velocities
Calculate speed on a distant time graph
Gradient of a line on a distance-time graph = speed
Displacement-Time Graphs
Displacement-time graph shows how displacement of an object changes with time
Gradient of a displacement time graph = velocity (not speed)
Gradient of a displacement time graph can be zero, positive or negative (unlike distance-time graph)
Negative gradient would represent a negative velocity (so indicates a reverse in direction)
Calculate acceleration from a velocity time graph
Gradient of a line on a velocity time graph = acceleration
Calculate displacement or distance from a velocity time or speed time graph
Area under graph line
SUVAT equation without any “s”
v=u+at
(Mnemonic: View Ugly AND Amazing Teapots)
SUVAT equation without any “a”
2s= (u+v) x t
(Mnemonic: TO See Us AND View Teapots)
SUVAT equation without any “v”
s=ut+(1/2)at²
(Mnemonic: See Ugly Teapots And HAVE A Tea TOO)
SUVAT equation without any “t”
v² - u² = 2as
(Default SUVAT equation)
