BuilderGrades 6–8⏱ 15 min

Speed and motion graphs

Set a walker’s speed for three parts of a trip and watch the distance–time graph appear. Steeper means faster; flat means stopped.

Standards: MS-PS2-26.RP.A.3b8.F.B.5

1Wonder

A runner, a turtle and a parked car. Could you tell which is which just by looking at a line on a graph?

Walk the graph

This activity needs a bigger screen

Turn your phone sideways, or open this lesson on a tablet or computer. The explanation and quiz below work here.

Speed, 0–4 s 1 m/s Speed, 4–8 s 0 m/s Speed, 8–12 s 2 m/s

Try this

Set all three speeds to 1 m/s and press Walk. What does the graph look like?
Make the middle part 0 m/s. What happens to the line while the walker stands still?
Make the last part negative. Which way does the walker go? Which way does the line go?
Press Match a graph and set the speeds so your line covers the dashed one.

Step 1 of 5

A walker goes 12 m in 4 s. Every second they cover 12 ÷ 4 = 3 metres. Their speed is 3 m/s.

Speed and graphs

\text{speed} = \frac{\text{distance}}{\text{time}}

On a distance–time graph, the slope is the speed. Steeper is faster, flat is stopped, and sloping down means moving back toward the start.

Question 1 of 5

A cyclist rides 30 m in 6 s. What is her speed?