Velocity
Velocity measures how much the displacement changes, every second.
It measures the rate of change of displacement in a specific direction, so it is a vector quantity.
Example
-
We walk 25km north in 5 hours, so to find our velocity:
-
displacement =
25km north -
velocity = displacement / time
-
v=25km\div5h=5kmh^{-1} -
Or, if we walk
400m north then 500m south in200s , finding our velocity: -
displacement =
400m-500m=100m south -
v=s\div t -
v=100m\div200s=0.5ms^{-1} south
\text{velocity}=\text{displacement}\div\text{time}
Where:
s is the displacement, measured in metres,m v is the velocity, measured in metres per second,ms^{-1} (m/s )t is the time, measured in seconds,s
This calculates the average velocity.
A van drives 200m in 10s. Calculate the velocity.
v=\frac st v=\frac{200}{10}=20 - Answer:
20ms^{-1}
A car drives 75m in 5s. Calculate the velocity.
v=\frac st v=\frac{75}{5}=15 - Answer:
15ms^{-1}
A car drives south 50m then north 150m, in 20s. Calculate the average velocity.
- displacement =
150m-50m=100m north v=\frac st v=\frac{100}{20}=5 - Answer:
5ms^{-1} north
A bike drives 10m in 20s. Calculate the velocity.
v=\frac st v=\frac{10}{20}=0.5 - Answer:
0.5ms^{-1}
A truck drives 240m in 8s. Calculate the velocity.
v=\frac st v=\frac{240}{8}=30 - Answer:
30ms^{-1}
A car drives 300m in 12s. Calculate the velocity.
v=\frac st v=\frac{300}{12}=25 - Answer:
25ms^{-1}
A van drives 600m in 15s. Calculate the velocity.
v=\frac st v=\frac{600}{15}=40 - Answer:
40ms^{-1}
A person cycles for 4h until reaching a destination 100km away. Calculate their average velocity.
v=\frac st v=\frac{100}{4}=25 - Answer:
25kmh^{-1}
A person cycles 100km north in 4h. Calculate their average velocity.
v=\frac st v=\frac{100}{4}=25 - Answer:
25kmh^{-1} north