Exploring friction

What forces result when one object touches another?

measuring the friction force

Materials

Place the board on a surface, with the hook upwards. Place a book (or other weight) on it. Then study the effect of various sized forces, by attaching the force scale to the hook and gently pulling.

1. If you don't pull very hard, nothing will happen. Discuss the forces acting on the board, from the point of view of the Law of Inertia and the Law of Force and Acceleration

2. If you pull hard enough, the board will begin to slide. Determine the size force needed to keep the board moving at approximately constant speed. Since the board is not accelerating, there is an equal and opposite force on the board -- the friction force -- which you have now measured.

3. Once the board is sliding, what happens if you try to exert a force that is larger than the friction force? What happens if you exert a force that is smaller than the friction force (while the board is moving)? Interpret these results from the point of view of the Law of Force and Acceleration.

4. write in your journal There are many other experiments you could do to study friction. Think of some, and do one.

Check the box when you are done:   

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