2017 AP Physics 1 Free Response #2
TLDRIn this educational video, Alan from Bothell STEM Coach demonstrates an experiment to determine the coefficient of static friction between a wooden board and a block. He suggests using a pulley system to measure the force required to initiate movement, emphasizing the importance of the normal force and mass in calculating static friction. Alan also addresses an inconsistency in a lab group's data, identifying an outlier and concluding that static and kinetic friction coefficients are generally not equal. Finally, he explains that adding a metal disk to the block does not change the coefficient of static friction, as it remains a property of the surfaces in contact.
Takeaways
- π¬ The video discusses an experiment to determine the coefficient of static friction between a flat wood board and a small wood block.
- π Alan, the Bothell STEM coach, provides a step-by-step explanation of the experiment setup and the measurements involved.
- π The experiment involves using a pulley system, a string, and a bucket filled with varying masses to apply force and measure static friction.
- 𧲠The normal force (N) is considered to be equal to the mass of the block (m) times the acceleration due to gravity (g), i.e., N = m * g.
- π To find the static friction force, the mass in the bucket is adjusted until the block starts to slide, indicating the point of static friction.
- βοΈ The coefficient of static friction (ΞΌ_static) is calculated by dividing the mass of the bucket by the mass of the block when the block starts to move.
- π A physics class with six lab groups is testing the hypothesis that the coefficient of static friction equals the coefficient of kinetic friction.
- π Lab group five's data is identified as an outlier, suggesting an error in their experiment as their results differ significantly from the other groups.
- π The conclusion drawn is that the coefficients of static and kinetic friction are not equal, based on the data provided by the lab groups.
- πΎ When a metal disk is added to the wood block, doubling its mass, the coefficient of static friction remains the same as it is a property of the surfaces in contact.
- π The video script also mentions alternative experimental setups, such as using an incline to measure the angle at which the block starts to slide.
- π The video concludes with a call to action for viewers to comment, like, or subscribe for more content on AP Physics 1 free response questions.
Q & A
What is the main topic discussed in the video script?
-The main topic discussed in the video script is determining the coefficient of static friction between a long flat wood board and a small wood block using an experiment.
What is the purpose of the experiment described in the script?
-The purpose of the experiment is to measure the coefficient of static friction between two wooden surfaces, which is the force that must be overcome to start moving an object resting on the surface.
What equipment is suggested for the experiment in the script?
-The script suggests using a pulley system with a string, a bucket to adjust the weight, and a scale to measure the mass of the block.
How does the script describe the experimental setup for determining static friction?
-The script describes an experimental setup involving a block on a board, a pulley system to apply force, and a bucket filled with masses to adjust the force until the block starts moving.
What is the role of the bucket in the experimental setup?
-The bucket is used to adjust the weight and thus the force applied to the block, which helps in determining the point at which static friction is overcome and the block starts to move.
How is the normal force calculated in the experiment?
-The normal force is calculated as the mass of the block multiplied by the acceleration due to gravity (N = m * g).
What is the relationship between the force of friction and the normal force in the experiment?
-The force of static friction is equal to the coefficient of static friction (ΞΌ_static) times the normal force (F_friction = ΞΌ_static * N).
What hypothesis is being tested by the physics class in the script?
-The hypothesis being tested is that the coefficient of static friction between the board and the block is equal to the coefficient of kinetic friction.
What conclusion should the students make about the hypothesis based on the data provided in the script?
-The students should conclude that the coefficients are not equal, as indicated by the data from the lab groups, with the exception of group five, which appears to be an outlier.
What happens to the coefficient of static friction when a metal disk is glued on top of the wood block?
-The coefficient of static friction remains the same because it is a property of the surfaces in contact, regardless of the mass of the block.
What is the significance of the incline method mentioned in the script?
-The incline method is another way to determine the coefficient of static friction by measuring the angle at which the block starts to slide down the inclined plane.
Outlines
π¬ Experiment to Determine Static Friction Coefficient
In this paragraph, Alan from Bothell STEM Coach introduces an experiment to determine the coefficient of static friction between a flat wooden board and a small wooden block. He suggests using a pulley system with a string attached to the block and a bucket to adjust the pulling force. The experiment involves measuring the mass of the block and the bucket, and calculating the normal force and the force of friction when the block starts to move. Alan explains that the coefficient of static friction can be found by dividing the bucket's mass (adjusted by adding weights) by the block's mass, just before the block begins to slide. He also discusses a scenario where a physics class tests the hypothesis that the coefficient of static friction is equal to the coefficient of kinetic friction, analyzing the results of six lab groups and identifying an outlier in the data.
π Analysis of Friction Coefficients and Hypothesis Testing
The second paragraph delves into the analysis of the data collected by the physics class, focusing on the comparison between the coefficients of static and kinetic friction. Alan points out that the data from lab group five is significantly different from the others, suggesting it as an outlier. He concludes that the hypothesis that the coefficients of static and kinetic friction are equal is not supported by the data, as the static friction appears to be higher in the majority of the groups' results. Additionally, Alan discusses a scenario where a metal disk is glued to the top of the wooden block, doubling its mass, and explains that the coefficient of static friction remains the same despite the increased mass, as it is a property of the surfaces in contact. He also briefly mentions the use of an incline to measure the angle at which the block starts to move, as an alternative method to determine the force of friction.
Mindmap
Keywords
π‘Static Friction
π‘Coefficient of Static Friction
π‘Pulley System
π‘Normal Force
π‘Mass
π‘Kinetic Friction
π‘Hypothesis Testing
π‘Outlier
π‘Incline
π‘Newton's Second Law
π‘Experiment Setup
Highlights
Introduction to the experiment on determining the coefficient of static friction between a wood board and a wood block.
Description of the experimental setup involving a pulley, string, and adjustable weights.
Explanation of how static friction is measured by observing when the block starts moving.
Use of mass to adjust the force exerted on the block and the role of gravitational acceleration.
Calculation of static friction force using the mass of the bucket and the block.
Method to experimentally determine static friction by adjusting the weight and measuring the block's mass.
Hypothesis testing by a physics class to compare coefficients of static and kinetic friction.
Analysis of lab group results showing consistency except for an outlier, suggesting the coefficients are not equal.
Identification of lab group five's data as an outlier due to significantly different results.
Discussion on the effect of adding a metal disk to the wood block on the coefficient of static friction.
Conclusion that the coefficient of static friction remains the same despite the increased mass.
Use of an incline to measure the angle at which the block starts sliding as an alternative method.
Comparison of different experimental setups and their validity in determining friction coefficients.
Clarification that the coefficient of static friction is a property of the surfaces in contact.
Final thoughts on the experiment and an invitation for feedback from the audience.
Acknowledgment of the completion of the question and a teaser for the next free response question.
Transcripts
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