Sticky Sneakers L2 Sticky Sneakers
S 8.2.a, 8.9.c
S 8.2.a, 8.9.c
Students conduct an investigation to see the
effect of friction on a moving object. Problem
Friction is a force that opposes an object’s
motion. Friction can be useful. For example,
Prepare for Inquiry friction between sneakers and the ground can
help an athlete to start and stop running. How
Key Concept does the amount of friction between a sneaker
Sneaker soles can be used to illustrate and a surface compare for different brands of
Skills Objectives Skills Focus
After this lab, students will be able to controlling variables, interpreting data
• control variables in an investigation of 2. Prepare a data table in which you can record
each type of friction for each sneaker.
friction Materials 3. Place each sneaker on a balance. Put masses
• interpret data to determine if the type of • three or more different brands of sneakers in each sneaker so that the total mass of the
sneaker is related to the type of friction • 2 spring scales, 5-N and 20-N, or force sensors sneaker plus the masses is 1,000 g. Spread
observed • mass set(s) • tape • 3 large paper clips the masses out evenly inside the sneaker.
Prep Time 30 minutes
Class Time 40 minutes Procedure 4. Tape a paper clip to each sneaker and
1. Sneakers are designed to deal with various attach a spring scale to the paper clip. (If you
Advance Planning friction forces, including these: are using force sensors, see your teacher for
Assemble the spring scales, paper clips, • starting friction, which occurs when you instructions.)
tape, balance, and mass sets. Bring in an start from a stopped position To measure
• forward-stopping friction, which occurs • starting friction, attach the paper clip to
assortment of sneakers and ask students the back of the sneaker
when you come to a forward stop
to volunteer their sneakers. • sideways-stopping friction, which occurs • forward-stopping friction, attach the
when you come to a sideways stop paper clip to the front of the sneaker
Safety • sideways-stopping friction, attach the
Review the safety guidelines in paper clip to the side of the sneaker
Teaching Resources Data Table
Sneaker Starting Friction (N) Sideways-Stopping Forward-Stopping
• Sticky Sneakers Student Worksheets Friction (N) Friction (N)
Have a student wearing sneakers
demonstrate three types of friction forces:
stopping, starting, and sideways. Ask: What 378 ◆
does friction depend on? (Sample answer:
Friction depends on the kinds of surfaces
involved and how hard the surfaces push
Introduce the Procedure Troubleshooting the Experiment
together.) Have students discuss how
Demonstrate how to zero and use a spring • Students should zero the spring scale each
different kinds of sneakers might have
scale. Show students how to measure the time it is used. If the spring scale is
different kinds of friction.
force of sliding friction with a spring scale by calibrated in grams, multiply by 0.01 to
pulling an object with a slow, constant obtain the approximate value in newtons.
motion. Tell students to pull an object • The spring scale should not be angled to
forward to measure forward-stopping the side or up and down while it is used, or
friction and sideways to measure sideways- the measurements will not be accurate.
Results will vary depending on the type of
Analyze and Conclude
1. The controlled variables are the adjusted
masses of each sneaker at 1,000g. The
5. The force necessary to make the sneaker 4. Drawing Conclusions Do you think that using manipulated variable is the sneaker; the
start moving is equal to the starting friction a sneaker with a small amount of mass in it is a
force. To measure starting friction, pull the fair test of the friction of the sneakers? Why or
responding variable is the amount of
sneaker backward until it starts to move. Use why not? (Hint: Consider that sneakers are friction.
the 20-N spring scale ﬁrst. If the reading is used with people’s feet inside them.) 2. Friction is a force that acts in the opposite
less than 5 N, use a 5-N scale. Record the
starting friction force in your data table.
5. Inferring Why did you pull the sneaker at a direction of motion. So, just as the sneaker
slow speed to test for stopping friction? Why begins moving the spring scale shows the
6. To measure either sideways or forward stop- did you pull a sneaker that wasn’t moving to
ping friction, use the spring scale to pull each test starting friction?
amount of friction opposing motion.
sneaker at a slow, constant speed. Record the 6. Drawing Conclusions Can you identify a 3. Students’ answers will depend on the
stopping friction force in your data table. relationship between the brand of sneaker types of sneakers tested. In general running
7. Repeat Steps 4–6 for the remaining sneakers. and the amount of friction you observed? If sneakers have more starting friction,
so, describe the relationship. What do you basketball sneakers exert more forward-
Analyze and Conclude observe that might cause one sneaker to grip
stopping friction, and tennis shoes exert
1. Controlling Variables What variables are the ﬂoor better than another?
more sideways-stopping friction.
controlled? Explain your answers. What are 7. Communicating Choose one of the brands
the manipulated and responding variables? of sneakers that you tested. In a paragraph, 4. No, in actual use there is much more mass
Explain your answers. (See the Skills Hand- explain why this sneaker is the best one to in the sneakers.
book to read about experimental variables.) wear while playing a particular sport or
activity. Be sure to include the results of this 5. You pull the sneaker at a slow speed to test
2. Applying Concepts Why is the reading on
lab in your explanation. stopping friction because your sneaker is
the spring scale equal to the friction force in
each case? sliding slowly along the ground or ﬂoor
3. Interpreting Data Which sneaker had the
Design an Experiment when you stop running. You pull a sneaker
most starting friction? Which had the most The strength of the friction force is determined that is not moving to test starting friction
forward-stopping friction? Which had the by both the design of the sneaker and the type of because your sneaker is not moving when
surface it presses against. Design an experiment
most sideways-stopping friction? you start running.
to ﬁnd out how various types of surfaces affect
the force of friction acting upon the sneaker. 6. Students’ answers may state that one
Obtain your teacher’s permission before carrying brand of sneaker provides better traction
out your investigation. than another because the soles are made of
different materials or have different tread
7. Students’ choice of a sneaker for a
particular sport should reﬂect their
knowledge of actions in the chosen sport
that would be best completed with the
sneaker with the appropriate starting
friction, sideways-stopping friction, or
forward-stopping friction from the table
comparing their frictions.
◆ 379 Extend Inquiry
Design an Experiment Students should
suggest different surfaces such as wood,
concrete, grass, or clay used for various
sports. They should choose one brand of
sneaker as the controlled parameter and
different surfaces as the variable parameter.