1. Coefficient of Friction
Setting up and executing an experiment.

2. QPOE2 What do you know about the given question How will you apply
what you found
Question
Application
Knowledge probe
Explanation
Evaluate
Prediction
Data Analysis
Investigation plan
Observation
How will you analyze
your data
How will you investigate
the question

3. QUESTION
Which of the following objects has the greatest coefficient of rolling friction between itself and the carpet floor?

4. What have we learned that would help us answer this question
What have we learned that would help us answer this question? The coefficient of static and sliding friction activity showed us that we can calculate m by dividing the friction force by the normal force (mass x acceleration due to gravity).

5. When an object is rolling, the only force on the object is the friction force between the object and its surface of contact. This means that the net Force is equal to the friction force. Newton’s 2nd Law of Motion Friction force equation So to calculate the coefficient of rolling friction, take the acceleration of the rolling object and divide by acceleration due to gravity

6. Equations of Motion for Uniform Acceleration
Equations Variables
vf = vi + at vi vf a t
d = ½ (vf + vi) t vi vf d t
d = vit + ½ at2 vi a d t
vf 2 = vi 2 + 2ad vi vf a d

7. Knowledge Probe What do we know about friction?
How do we calculate the coefficient of friction?
Which kinematic equations would help us?
What materials do we need?
What values are we going to measure?
What types of errors should will we encounter?
How many measurement should we take?

8. PREDICTION
Which object would have the greatest coefficient of rolling friction between itself and the carpet floor? Tennis ball, Marble, steel sphere, racquetball Why? Justify your prediction. Tennis ball – rough fuzzy surface Marble – smooth all around Steel sphere – heavy, smooth, slow to start Racquetball – smooth, kinda heavy

9. Investigative plan
Determine the procedures with which we can obtain the values needed in the knowledge probe which in turn will answer the QUESTION. Material list: ball, ramp, stopwatch, meter stick, carpeted area, pencil and paper, calculator Procedure: 1. Find the area to conduct the experiment 2. Gather the materials 3. Set up the experiment with the height being 15 cm 4. Release the ball from the top of the ramp 5. Measure the distance from the bottom of the ramp to where it stops. 6. Measure the time from the bottom of the ramp to when it stops 7. Record the data in the table 8. Repeat the process 5 times 9.

10. OBSERVATION
What values are measured? How many times do we repeat the trials?
Object: Tennis Ball
displacement
time
Trial 1
Trial 2
Trial 3
Trial 4
Trial 5

11. Data analysis What information can be derived from the observation?
Object: Tennis Ball
displacement
time
Initial velocity
acceleration
Trial 1
Trial 2
Trial 3
Trial 4

12. EVALUATION
Using the acceleration that was calculated rom the data analysis, determine the coefficient of friction.
Object: Tennis Ball
displacement
time
Initial velocity
acceleration
Coefficient m
Trial 1
Trial 2
Trial 3
Trial 4

13. EXPLANATION
From the evaluation, ______________ has the greatest rolling coefficient of friction. Offer reasons why the object has the greatest rolling friction