You are driving down a straight highway at 20 m/s (72 km/h) on a foggy night. Suddenly you see
a truck stopped directly in front of you a distance d down the roadway.
Here are my axes:
How to choose a scale
Choose the x axis scale.
In order to show the 1 s reaction time, choose 2 or 5 divisions
for one second. Since you may not know how long the graph should extend in time, it might
be wiser to choose 2 division/second because this leaves more room.
Choosing 3 or 4 division per second would be
ok, but creates
subdivisions at more inconvenient numbers (for example, 0.3333 s or 0.25 s).
Choose the y axis scale.
The maximum velocity is 20 m/s. If you choose each division to represent
2 m/s then the graph's height will be 20 divisons which is 2.5 inches or 100 mm.
That's convenient. Choosing each division = 5 m/s would be ok too, but gives
a height of only 1 inch or 20 mm which is a little short.
What to do
Draw the graph.
After you have drawn your graph
compare it to our graph
and continue.
Go back
Check my answer