Testing Forces With Ramps

You will learn how to design a simple experiment that tests how force changes the way an object moves.

Think about a toy car rolling down a ramp at recess. A force is a push or a pull that can make something start moving, stop moving, or change direction. When you lift one end of the ramp higher, gravity pulls the car down the slope with more force. The car rolls faster and travels farther across the floor. That is a force doing work in a system, which is a group of parts that work together, like the car, the ramp, and the floor.

To design a good test, you change only one thing. Scientists call that one thing the variable. In the ramp test, the variable could be the height of the ramp. You might prop the ramp on one book, then two books, then three books. Everything else stays the same. You use the same car, the same ramp, and the same smooth floor every time.

Next, you decide what to measure. You could use a meter stick to measure how far the car rolls after it leaves the ramp. Roll the car three times at each height and write the numbers in a chart. Doing it three times helps you spot mistakes and see a real pattern.

Then you look at your data and find the pattern. If the car rolls farther each time you add a book, you can say that a greater force made the car move farther. A balloon rocket on a string works the same way. A bigger puff of air pushes the balloon with more force, and the rocket zips farther down the string.

Try it: If you want to test how the size of the balloon changes how far your balloon rocket travels, what one thing should you change, and what should you keep exactly the same?