Constant velocity car

1. Tap a mass in the Mass set tray to stack it on the car. Use Remove top mass or Clear masses to change the load.
2. Press Start to run the car. Each run lasts 10 seconds. A tape flag drops at the front bumper every second.
3. Watch the readouts at the top. They show the total mass, speed, time, and distance.
4. Read the Data table as it fills in. d is where the front bumper is. Δd is how far it moved in that one second.
5. Read distance off the meter sticks too. Each stick goes from 0 to 100 cm. Then the next stick starts over at 0.
6. When a run ends, it is saved to the Position vs time graph. Change the mass and run again to compare the lines.
7. Turn off Show speed readouts to find the speed from the graph yourself. Turn on Add measurement error to practice drawing a best-fit line.
8. Press Reset run to try again. Press Clear saved runs to erase the graph.

Velocity is how fast something moves and in what direction. Constant velocity means the speed and direction do not change.

This car moves at a steady speed. So it covers the same distance every second. Look at the tape flags. They are spaced out evenly. Look at the Δd column. Every number is about the same.

On a position vs time graph, constant velocity makes a straight line. The slope of the line is the speed. Slope means how steep the line is. A steeper line means a faster car.

The car has a small battery motor. The motor can only push so hard. When you add mass, the motor has more to carry. So the car settles at a slower steady speed.

The car is still at constant velocity. It is just a slower constant velocity. Its line on the graph is still straight, but it is less steep.

If you add too much mass, the motor stalls. That means it is too weak to move the car at all.

Speed: v = 30.0 cm/s × (1 − added mass ÷ 3000 g)

Distance: d = v × t. The car starts at 0 cm.

Average speed: v = d ÷ t.

The empty car is 250 g. With nothing added it moves 30.0 cm/s. Adding 3000 g stalls the motor. Every position is measured at the front bumper.