Displacement and velocity - Higher
The only difference between velocity and speed is that velocity has a direction, and so is a vector quantity.
Average velocity = \(\frac{\text{displacement}}{\text{time}}\)
Displacement is the distance moved in a straight line, in a given direction, from the starting point.
Displacement is a vector quantity as it has size and direction.
Question
If a car travels 24 m east in 3 seconds, what is its velocity?
Displacement = 24 m east.
Velocity = displacement 梅 time.
Velocity = 24 m 梅 3 s = 8 m/s east.
The velocity of the car is 8 m/s east.
Question
You walk all the way around the house in the diagram in 20 seconds.
a) What is your speed?
b) What is your velocity?
a) speed = distance moved 梅 time taken
distance moved = 10 m + 10 m + 10 m + 10 m = 40 m.
Speed = 40 m 梅 20 s = 2 m/s.
Your speed is 2 m/s.
b) Velocity = displacement 梅 time
displacememt = 0 (Your displacement is nothing. You have ended up at your original position. No net distance in a straight line has been made between the start and end point.)
velocity = 0 m 梅 20 s = 0 m/s.
Your velocity is zero.