OVERCOMING FRICTION 1

HYPOTHESIS

What happens to friction when we use wheels to roll an object instead of sliding it?

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MATERIALS

2 science books	1 bucket	15 weights
1 hook	brown paper	5 round pens or pencils
	1 loop of string	1 piece of masking tape

PROCEDURE

1. Tape the brown paper to the desk. Put the loop of string around one science book.

2. Place the book on the brown paper. Use the hook to attach the bucket to the string.

3. Add weights to the bucket one at a time until the book moves or starts to slide. Be sure and add the weights gently. Record the number of weights needed.

4. Repeat using 2 books.

NUMBER OF BOOKS	WEIGHTS NEEDED
NUMBER OF BOOKS	BROWN PAPER	ROLLERS
1
2

5. Put the pencils down on the brown paper, evenly spaced and parallel to the edge of the desk. Repeat the experiment with the book on the top of the pencils. The pencils will act as rollers and will make a difference in the number of weights needed.

CONCLUSION

What type of simple machines are rollers?

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What affect did they have on friction?

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