Force = Mass x Acceleration

In this class we talked about Newton’s second law, Force= mass x acceleration. I set up a bunch of wallpaper tubes (these could also be ramps) on a smooth surface, a low pile carpet, and fake grass. I set them up at two different angles. The kids put one ball at the bottom of the ramp and let one ball go at the top of the ramp. I also had a few different types of balls that were different sizes and different densities. Then they observed how the ball at the bottom of the ramp moved after it was hit by the ball that rolled down the ramp.

When the ramp is more upright the acceleration of the ball will be greater and so will the striking force. The force will also be greater when the mass of the striking ball is greater. It will take a greater force to move a ball at the bottom of the ramp when it’s mass is greater. Friction on the ground will require more force to move the struck ball.

I had the kids break up into small groups and try these different conditions. Then I asked them what the observed for each variable and they recorded that in their notebooks.

Force Diagrams

I showed the class a force diagram with gravity, the normal force, friction. I had discussed gravity in a previous class. Then, I mentioned that the normal force and friction are fundamentally caused by the interaction of electrons from different atoms. We had talked about atoms and molecules in the previous class.

This can get a little hectic after a while with all of the balls moving around, but the kids seemed pretty engaged. Just try to get the kids to try all of the floor surfaces.

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