Friction Inquiry Lab

Problem: How does friction affect motion?• Friction is always present. Sometimes we want friction. For example,

friction between tires and the road allows a car to be steered safely and maintain its direction when moving. Other times we want to reduce friction. Putting oil on a bicycle chain allows it to work more effectively with the gears. This investigation explores the different effects of friction.

Lab, Part 1: How does air friction affect speed?• Write a hypothesis for this problem statement.• Materials: • Energy car and track• Physics stand• Photogates• Items to create friction: paper plates, tongue depressor, paper, tape, other

teacher approved items.

Experiment!

• You will need to write a procedure to test how air friction affects speed. It must include:• A control group• 2 experimental groups

• Next, create a data table for your data collection. Remember to include what you will analyze.

• Must be handed in to receive permission to begin experiment.

Lab, Part 2: Rolling vs. Sliding Friction• Problem: What type of friction has the greatest affect on the car’s

motion, sliding or rolling?• Write a hypothesis for this problem statement.

• Set up the energy track using one rubber band. Place photogate A on the mark just ahead of the flag on the sled. Place photogate B 45cm from photogate A. • Launch the friction sled, pay attention to your times, if one seems off,

do not use the data and repeat that trial.

Data Collection

• 2 data tables (one for rolling friction, one for sliding):Trial Time

through ATime through B

Time from A to B

Speed through A

Speed through B

Acceleration

1

2

3

Data Analysis

• For each data table, write 2-3 sentences describing what the data tells you about the experiment. This can include averages of the data and further analysis.

Conclusion

• Part 1• Was your hypothesis correct?• Explain where the frictional force on the sail comes from. • Could you increase the friction, decrease it? How?• Is there any other source of friction?

• Part 2• Was the hypothesis correct?• What happened to the car, did it accelerate or decelerate? What does this tell you about

the types of friction. • How could you change the amount of rolling or sliding friction?

Out of all three types of friction, which had the greatest affect on the motion, the least? Why do you think that?