### What must you do to make sure that you win the Science Olympiad?

In order to find the velocity from a position-time graph, you will simply need to find its slope. This is because the definition of velocity is the change in displacement over the change in time, where displacement is a measure of distance relative to a fixed point. The most common example would be the speed of vehicles, in which we would all be familiar with the unit miles per hour. It is a measure of how many miles over a certain elapsed hour, showing displacement in miles and time in hours.

For a school science olympiad, the student with the fastest vehicle will win. You have decided to enter the competition because your science teacher will give you 25 extra credit points for the semester if you win. So far, you have built three different model cars and tested their motion with a stopwatch and ruler. In the end, you would choose to use one for the competition.

### Creative Applications

1. You make position-time graphs for each of the three cars that you built. How can you tell which car is the fastest?

2. Let’s say, for example, that car 1 has a slope of 2, car 2 has a slope of 3, and car 3 has a slope of 4. Which car are you going to use for the competition?

3. Why might it be erroneous to start measuring the cars from rest? How should we conduct the measurement to ensure that we make the right decision?