Distance-time graph in m and s: (0, 0) (4, 40) (6, 40) (10, 0), find…

Step by step, with the reason for every step · Distance-time graphs · Algebra 1

Step by step

Question: the distance-time graph joins (0, 0) (4, 40) (6, 40) (10, 0), find the speed of each part.

distance-time graph: (0, 0) (4, 40) (6, 40) (10, 0)

Across: the time in seconds.

Up: how far from the start, in m.

Going up: moving away from the start.

Flat: stopped.

Going down: coming back.

Speed is the distance divided by the time.

On the graph that is the slope: up over across.

speed = distancetime = slope

Part A: 40 m in 4 s.

40 divided by 4 is 10 m/s.

A: speed = 404 = 10 m/s

Part B is flat.

The distance does not change: 0 m in 2 s.

The speed is 0: stopped.

B: speed = 02 = 0 m/s

Careful!

The flat part is high on the graph, but height is distance, not speed.

Flat means stopped.

Careful: not speed = 40 m/s ✗

Part C: 40 m in 4 s, coming back.

40 divided by 4 is 10 m/s.

C: speed = 404 = 10 m/s

Let's check: speed times time gives back each distance: 40 and 40.

So it is right!

10 × 4 = 40, 10 × 4 = 40

Let's look back.

First: read the graph.

Then: speed of each part.

Last: check.

Answer

C: speed = 404 = 10 m/s

Try this one yourself, then check:

distance-time graph: (0, 0) (4, 80) (6, 80) (10, 0)

Show the answer

A: 20 m/s, B: 0 m/s, C: 20 m/s