Introducing Friction

Part I:  Review Force and introduce Friction

1. Force is a push or a pull.
   1. Demonstrate and ask students to imitate pushing their hands together.
   2. Demonstrate and ask students to imitate pulling their hands apart.
   3. Friction is a force caused when two objects push or rub against each other.  
2. Friction is the force that slows thing down.
   1. Demonstrate and ask students to rub their hands together.
   2. Ask “What do you notice?”  Their hands get warmer.
   3. Friction always gives off some heat.
3. Explore friction with wooden spools and sand
   1. Push and pull a spool through sand, standing up and on its side.
   2. The sand makes it harder to move the spool because it rubs against the spool and creates “friction.”

Part II  Measuring friction:

1. Spool on a ramp standing up
   1. Place the spool, standing up at the end of an 18 inch wooden board.
   2. Slowly lift the board until the spool moves.
   3. Observe and/or measure the height of the board when the spool moved.
2. Spool on a ramp on its side
   1. Place the spool, on its side at the end of an 18 inch wooden board.
   2. Slowly lift the board until the spool moves.
   3. Observe and/or measure the height of the board when the spool moved.
3. Objects on a ramp
   1. Place each object one at a time on the end of the board and slowly lift the board.
   2. Observe and/or measure the height of the board when the object moves.