Friction as a force Friction is a force which prevents easy movement between two objects that are in contact.
Activity Testing the grip of shoes
Apparatus Shoe, ruler, rubber band, sticky tape
Method 1. Cut a rubber band so that it is one length rather than a loop. 2. Tape one end of the rubber band securely to the back of the shoe you are testing. 3. Hold the rubber band and measure the length of it from the shoe to your fingers. 4. Pull on the rubber band as shown in the diagram. Try to keep the rubber band as level as possible.
Fig. 2 Testing the grip of a shoe.
5. Measure the length of the rubber band just as the shoe starts to move. 6. Repeat these steps with other shoes but with the same length of rubber band.
Questions The more force that is needed to move the shoe, the longer the rubber band will be. 1. Why was the rubber band longer just before moving some shoes than others? 2. What factors affected the amount of force needed to move each shoe?
In the above activity, the more friction there was between the shoe and the ground, the more force it took to get the shoe to move. There were many factors that affected how much force it took to get the shoe to move. Some shoes have very smooth soles while others have more grip. Some of the shoes are very light while others are much heavier. Friction is affected by: 1. Downward force: The more the object is pushed down on a surface, the greater the friction between them.
2. The roughness of the surface: The rougher the surface, the greater the friction. A. Shoe on the ground.
Friction is a force which prevents easy movement between two
objects that are in contact.
B. Shoe pushed down onto ground.
C. Shoe with more grooves or grip.
Fig. 3 Friction increases when downward force increases (B), and when the roughness of a surface increases (C). 315
