Scalar quantity
has magnitude (size) only eg: TIme, mass, distance
Vector Quantity
has magnitude (size) and direction. represented by an arrow. The length of the arrow represents the size of the vector.
Distance
The length of the path taken by an object or body. a scalar quantity measured in m or km
Displacement
the straight line distance between the start and end of an objects path. A vector quantity measured in m or km with a direction.
Speed
The rate of change of distance scalar measured in m/s or km/h. Speed = Distance / Time
Velocity
The rate of change of displacement vector measured in m/s or km/h. Velocity = displacement / time
converting
m/s x 3.6 = km/h
km/h / 3.6 = m/s
Acceleration
The rate of change of velocity (speeding up and slowing down) vector
measured in m/s or km/h squared.
Acceleration formula
a = v-u/t
a = acceleration (m/s squared)
v = final velocity (m/s)
u = initial velocity (m/s)
t = time (s)
Calculation Rules
- List all values in a question
- Choose a formula that contains all the variables
- Substitute values into formula
- Rearrange if required and solve
- Make sure final answer has units and direction
v2 = u2 + 2as
Good when you dont know time
s = ut + 1/2at2
Good when you dont know final velocity
