Cutting an Apple

Purpose:

Demonstrate the use of force for children to see how friction can combine with force to produce different outcomes.

Materials:

Apple (red and green)

4- 5in X 5in Pieces of regular weight printer paper

Straight edges, sharp knife

Procedure:

• Have students rub hands together
• Ask questions
• Show Students Materials
• Ask pre demo questions
• Cut 1 piece of paper with knife (sawing motion)
• Fold second piece of paper over sharp part of blade
• Press paper wrapped knife firmly against top of apple
• Using two hands press knife firmly (not sawing motion) through apple
• Pull knife and paper out
• Show un-cut paper to class
• Ask post demo questions

Questions to ask:

Hand example~

What happens when you rub your hands together?

Why do you think that happens?

What is another example of rubbing two objects together to get a reaction?

Pre demo~

What do you think will happen when I run this knife across this paper?

Do you think the same thing will happen when I cut this apple with the paper between the knife and the apple?

Post demo~

Did your prediction of what would happen to the paper come true?

Why do you think the paper didn’t get cut?

Thinking back to the way I did the experiment, what thing did you notice that may have caused the paper not to be cut?

Do you think the demo would have turned out different if I had used a butter knife?

How could I change the apple? (cooked, dried)

Do you think every fruit would react the same way?

Could there be a fruit that would not cut? Why?

Who could use this kind of knowledge in their real job?

Reference Sources:

Cobb, Vikki. I bet you can’t

http://classroom.jc-schools.net/sci-units/force.htm#3

http://www.school-for-champions.com/science/forces.htm