Distance Speed Time
Content
- Distance, Speed, Time
- Example
- Conversion of Speed Units
- Distance - Time Graph
- Speed - time Graph
Distance, Speed, Time
Distance = Speed x Time
Time = Distance / Speed
Speed = Distance / Time
Average Speed = Total Distance Travelled / Total Time Taken
Example
Melissa cycles at 10 km/h for 30 minutes and walks 4 km at an average speed of 2 km/h. Find (a) the distance she cycled (b) the time she took for walking (c) average speed for the whole journey.
(a) the distance she cycled
Distance = Speed x Time = 10 km/h x 30 minutes = 10 km/h x (30/60) h = 5 km
(b) the time she took for walking
Time = Distance / Speed = 4 km / 2 km/h = 2 h
(c) average speed for the whole journey
Average Speed = Total Distance Travelled / Total Time Taken
= (5 + 4) km / (1/2 + 2) h
= 9 km / 2.5 h
= 3.6 km/h
Conversion of Speed Units
Distance – Time Graph
Time is in the x axis. Distance is in the y axis.
Speed is the gradient of the graph.
Speed – Time Graph
Time is in the x axis. Speed is in the y axis.
Distance travelled is the area under the graph.
Acceleration is the gradient.
Questions
- Express 36 km/h in m/s
- Express 20 m/s in km/h
- A bus starts at 0900 travels 100 km at 60 km/h. Find the time when it reaches its destination.
- Alan's school is 2 km away from his home. He cycles to school at an average speed of 10 km.h. Find how long he will take to reach his school.