Lesson Code (Course - Master Objective # - Benchmark # - Lesson # - #)

  • Science 8-2-1-1

Title - Author

  • Friction and It’s Effects on Force-Duane Kimble

Benchmark/Expectation

  • Recognize how forces affect motion.
  • Overarching Question: How will sliding friction on various surfaces affect applied force?

Relevant Goals

Show-Me
Process / Show-Me
Science Content / Missouri
Science GLE(s) / SJSD / National
(5-8, 9-12)
  • 1.6
  • 1.8
/
  • 1
/
  • FM.2.2.A.7.a & b
  • FM.2.2.D.7.a, b, c, & d
/
  • 6
/
  • B

Learning Path

Previous Learning / Targeted Learning / Future Learning
  • FM.2.2.A.4.a.: Identify the forces acting on the motion of objects traveling in a straight line
  • FM.2.2.A.4.b.: Recognize friction as a force that slows down or stops a moving object that is touching another object or surface
  • FM.2.2.A.4.c.: Compare the forces (measured by a spring scale in Newtons) required to overcome friction when an object moves over different surfaces (i.e., rough/smooth)
  • FM.2.2.D.4.a.: Recognize that balanced forces do not affect an object’s motion
  • FM.2.2.D.$.b.: Describe how unbalanced forces acting on an object changes its speed (faster/slower), direction of motion, or both
  • FM.2.2.D.4.c.: Explain how increasing or decreasing the amount of force on an object affects the motion of that object
  • FM.2.2.D.4.d.: Explain how the mass of an object (e.g., cars, marbles, rocks, boulders) affects the force required to move it
  • FM.2.2.D.4.e.: Predict how the change in speed of an object (i.e., faster/slower/remains the same)is affected by the amount of force applied to an object and the mass of the object
/
  • FM2.2.A.7.a.: Identify and describe the types of forces acting on an object in motion, at rest, floating/sinking (i.e., type of force, direction, amount of force in Newtons)
  • FM2.2.A.7.b.: Compare the forces acting on an object by using a spring scale to measure them to the nearest Newton
  • FM2.2.D.7.a.: Compare the effects of balanced and unbalanced forces (including magnetic, gravity, friction, push or pull) on an object’s motion
  • FM.2,2,D.7.b.: Explain that when forces (including magnetic, gravity, friction, push or pull) are balanced, objects are at rest or their motion remains constant
  • FM.2.2.D.7.c.: Explain that a change in motion is the result of an unbalanced force acting upon an object
  • FM.2.2.D.7.d.: Explain how the acceleration of a moving object is affected by the amount of net force applied and the mass of the object
/
  • Newton’s Laws of Motion explain the interaction of mass and forces, and are used to predict changes in motion
  • Recognize that inertia is a property of matter that can be described as an object’s tendency to resist a change in motion, and is dependent upon the object’s mass (Newton’s First Law of Motion)
  • Describe the effect of a change in mass of an object on the inertia of that object (Newton’s First Law of Motion)
  • Predict and explain the effect of a change in force and/or mass on the motion of an object (Newton’s Second Law of Motion

Possible Misconceptions

  • Constant motion requires a constant force-if you want to keep moving along a horizontal track, you have to keep pushing, otherwise you will run out of force and just stop. This represents a failure to distinguish the role of friction as a separate force.
  • If a body is not moving there is no force acting on it.
  • The amount of motion(speed and distance traveled)is proportional to the amount of force.
  • If a body is in motion, there is a force acting upon it in the direction of motion.
  • Force is something that is a property of an object and gets used up.

Teacher Notes

Engage

  • Clear a path in front of the room.
  • Set a desk or small table at one side of the room.
  • Select a volunteer student (a small student) to assist in a demonstration.
  • Have the student stand on the opposite side of the table/desk facing teacher.
  • Facing each other, both teacher and student place hands on opposite sides of table/desk.
  • With both student and teacher pushing in opposite directions, have student attempt to push you across the floor. The desired result is to have the student push harder than you without yourself moving anywhere. On the day that this activity is performed, The teacher needs to be wearing shoes that will not slide.
  • Stop pushing after approximately five seconds.
  • Repeat activity with teacher and the table/desk both standing on super slider furniture movers

  • Formative Assessment(s):
  • Ask students to record what they observed and what they believe happened to cause a change in motion.
  • Based only on what they observed, ask/discuss with students what they believed caused a change in the motion.

Explore

  • Purpose: To investigate the relationship between sliding friction and applied force.
  • Materials: laptop computer, Vernier data-collection program, Vernier Dual-Range Force Sensor, paper clip, calculator, masking tape, duck tape, metric ruler, two 4” x 4” x 6” block of wood with hook at one end, course-grained sandpaper, small super slider furniture movers or small felt strip floor protectors, 1” x 6” x 4’ piece of wood.
  • The block of wood could be prepared prior to investigation. Screw the hook into the center of one end of the block. Attach a large paper clip to the hook. Attach 4 self-adhesive felt strips on one side of the block. Cut out a piece of sandpaper large enough to cover one side of the wood block. Using duck tape, attach the piece of course-grained sandpaper on the side opposite the felt strips.
  • Using the available materials, discuss with students what they believe to be a general procedure to investigate the relationship between sliding friction and applied force. In discussing the procedure, allow for flexibility of investigation among each group.
  • Group into eight teams. Assign roles to each student on each team. Teams are to discuss and establish a problem and a hypothesis on the experimental design lab form.(You may want to establish the Problem as a class.)
  • Connect the Venier Dual-Range Force Sensor to the computer interface by using the Venier Lab Pro or the Venier Go Link.
  • If you are using a Dual-Range Force Sensor, set the range switch to 50 N.
  • Screw the pull pole into the force sensor.
  • Open Logger Pro.
  • Click on data collection icon(graph & stopwatch)/Change time frame to 5 seconds.
  • Click on analyze, then click on statistics.
  • Measure a distance on the 4’ piece of wood and mark the beginning and end with masking tape. The distance is not important. This allows students to experiment with measurements and establishes a standard unit of measure for their investigation. Students may make mistakes with the length of the pulling distance not being a workable distance. Some students may need help in establishing a workable distance.
  • Place the block of wood (wood side down) against the front edge one piece of the masking tape. Hook the force sensor to the paper clip on the wood..
  • Begin data collection by clicking on the green collect arrow. Pull the force sensor and wood block so that the wood completes the distance between the two pieces of tape in five seconds.
  • Click on autoscale graph icon (graph with A).
  • Click on experiment and store latest run.
  • Record the “mean” Newton force on the Experimental Design data table.
  • Repeat data collecting, storing and recording with the wood side two more times.
  • Have all teams stop at this point to discuss the data. Ask the students what variables could be changed to affect the data collection.
  • Repeat the previous step three times on the felt side and three times on the sandpaper side.
  • Complete filling out the remainder of the Experimental Design Lab form.

  • Formative Assessment(s):
  • Discussions and questions between teacher and individual groups will occur about methods and thought processes during investigation.

Explain

  • The following terms are relevant in this investigation and are “tied-in” to one another during the activity. These are terms students should be able to use when explaining forces & friction. Conduct a discussion with the students about what they observed during the engage and explore activities. The following describes the engage activity, but is easily applied to the explore activity. There is a force on the table/desk before anyone touches it. There is a contact and balanced force between the chair and the floor with gravity pulling and the floor pushing. Friction prevents the table/chair from moving. Newton’s 1st law tells us that because the forces are balanced and the object is at rest, it will remain at rest. When the student and teacher both push on the chair in opposite directions a force is applied. Since they are touching it another contact force occurs. If no movement occurs the forces remain balanced. Friction between the floor and shoes helps prevent motion. If students use the word “Friction”, have them explain how they perceive friction. When the teacher stands on the sliders, friction is reduced. An unbalanced force occurs and Newton’s 1st Law tells us that the object will remain in motion until an unbalanced force acts on it (friction). During the lab activity when the additional block of wood is added, the additional mass causes a greater downward force. As a result of the greater pressure, friction increases and the pulling force becomes greater.
  • A force is a push or a pull.
  • A contact force is when one object pushes or pulls another object by touching it, the first object is applying a contact force to the second.
  • Gravity is the force of attraction between two masses.
  • Friction is a force that resists motion between two surfaces that are pressed together. Friction can be useful or harmful.
*Friction can be useful when slowing or stopping a car.
*Friction can be harmful on a car’s engine.
  • The overall force acting on an object when all forces are combined is called the net force.
  • Balanced forces cannot change an object’s speed or direction.
  • An unbalanced force is needed to change an object’s motion.
  • Newton’s first law states that objects at rest remain at rest, and objects in motion remain in motion with the same velocity, unless acted upon by an unbalanced force.

  • Formative Assessment(s):
  • Discuss each team’s hypothesis and conclusion with the class and allow teams to revise parts of their statements as needed.

Elaborate

  • A greater pulling force is needed if the mass becomes greater.
  • The pulling gravitational force becomes greater as mass increases causing a greater frictional and contact force.
  • Have each team predict what the pulling force in Newtons will become if the mass is doubled. Students should be able to justify their prediction.
  • Based on the students written prediction, have the students draw a prediction line on the graph using the prediction icon.
  • Have each team double the mass of wood by giving each team another equal size block of wood to be placed on top of the first.
  • Repeat the previous procedure for collecting data on force in Newtons.
  • Allow students to explore other variables that may affect frictional force or design a new experiment to test frictional force.

  • Formative Assessment(s):
  • Discussions and questions between teacher and individual groups will occur about methods and thought processes during investigation.

Evaluate

  • Summative Assessment(s):
  • Use data from completed Experimental Design lab form from each student to assess student learning.

Additional Resources

  • Text:
  • Websites:
  • Video:
  • Experimental Design Lab Form: On following pages

Teacher Review

Name______

Hour______Date______

Experimental Design/Forces & Motion

(The term, “Friction” may not be used on this report.)

Problem(If & will): ______

______

Hypothesis(claim/If, then, because):______

______

Materials: Laptop computer, Vernier data collection program, Vernier Dual-Range Force Sensor, paper clip, masking tape, calculator, metric ruler, two 4” x 4” x 6” block of wood with hook at one end, course-grained sandpaper, small super slider furniture movers or small felt strip floor protectors, one 1” x 6” x 4’ piece of wood

Procedure:

1. Connect the Venier Dual-Range Force Sensor to the computer interface by using the Venier

Lab Pro or the Venier Go Link. Turn-on computer and open Logger Pro.

2. Attach the pull arm to the force sensor. Switch to 50N on force sensor.

3. Measure a distance of 60 cm on the 4’ piece of wood and mark a beginning and end with

masking tape. Try to center the 60 cm measurement on the wood.

4. Click on data collection icon(graph & stopwatch)/Change time frame to 5 seconds.

5. Click on analyze then click on statistics.

6. Place the block of wood (with hook) wood side down against the front edge of one piece

of the masking tape. Hook the force sensor to the wood with a paper clip. The force sensor

and wood should both begin and end on the 1” x 6” piece of wood.

7. Begin data collection by clicking on the green collect arrow. Pull the force sensor and wood

block so that the wood completes the distance between the two pieces of tape in 5 seconds.

8. Click on autoscale graph icon(graph with A).

9. Click on experiment and store latest run.

10. Record the “mean” Newton force in Newtons(N) on the Experimental Design data table.

11. Repeat data collecting, storing, and recording with the wood side down two more times.

12. Repeat the previous step 3 times on the felt side and three times on the sandpaper side.

Data Table/Force in N

Identify the control
and the variables / Control
______/ I.V. #1
______/ I.V. #2
______
Trial #1
Trial #2
Trial #3
Average

Independent(Manipulated)Variables(I.V.)______

Dependent(Responding)Variable:______

Constants:______

Identify the control setup and the experimental setup. Explain what led you to identify each setup

______

Bar graph the “average” results from the data table. Title, number, and label the graph.

______

______

Conclusion(claim, evidence, reasoning):

*Was the Hypothesis/Claim supported?

*What meaningful evidence or data in this investigation supports or denies your claim?

*Based on evidence, what explanation or reasoning can be offered for the findings?

______

Name______

Hour______Date______

Further Investigation/Forces & Motion

Prediction: What do you believe will happen with the pulling force in Newtons if the mass of

the wood block is doubled (be specific)? Supply your reasoning to justify your prediction.

______

Procedure:

*Repeat the steps from the previous procedure, but double the mass of the wood block by

placing an equal size wood block on top of the first. Test the wood surface only.

*Investigate two other variables of your choosing that may affect the pulling force or design a

new experiment to investigate friction.

*Record the data from the other two variables.

Data Table/Force in N

Identify the
the variables / Two
Wood Blocks / I.V. #1
______/ I.V. #2
______
Trial #1
Trial #2
Trials #3
Average

*If time permits, you may investigate more than the two additional variables of your own

withoutrecording results.

Conclusion(evidence, claim, reasoning)

*Was your Prediction/Claim supported?

*What meaningful evidence or data in this investigation supports or denies your claim?

*Based on evidence, what explanation or reasoning can be offered for the findings?

______