Your task. Choose the starting values, then sketch the s-t, v-t and a-t graphs for the first 10 seconds on paper. Press Start, watch the car, then tick Show the graphs to check your sketches. The graphs are drawn as the car moves. Use Try an example for typical cases, or find the starting values that make the car stop, turn round or leave the road.

How are the three graphs linked?

Slope: the slope (gradient) of the s-t graph is the velocity. The slope of the v-t graph is the acceleration.

Area: the area between the v-t graph and the time axis is the change in displacement. The area under the a-t graph is the change in velocity. Area below the time axis counts as negative.

v = u + at
s = s₀ + ut + (1/2)at²

The acceleration stays constant in this lab, so the a-t graph is a flat line, the v-t graph is a straight line and the s-t graph is a parabola. If a and u have opposite signs, the car slows, stops for an instant (the s-t graph has its turning point where the v-t graph crosses zero) and then comes back.

Things to look for. (1) When the velocity is positive, is the s-t graph rising or falling? (2) What does a steeper s-t graph mean? (3) When the car is slowing down, what are the signs of v and a? Is the acceleration then positive or negative? (4) For “Turning round”, why is the area under the v-t graph zero, and what does that say about where the car finishes? (5) Is the distance travelled the same as the displacement?

Notes. Displacement is measured from the 0 m mark, and right is positive. The vertical scales of the graphs change to fit the motion, so look at the numbers on the axes when you compare two runs. The run stops after 10 s, or sooner if the car reaches the end of the road (±50 m).