Friction: Investigation 3 –
This Investigation is designed to help you to answer the following Focus Questions:
- What is the relationship between weight and frictional force?
- What is the relationship between the surface area of an object in contact with another surface and the frictional force between two surfaces?
Note: These questions are located in your SDR at the beginning and end of the Investigation.
As a class, read the Background(s) in Investigation 1. When finished, discuss the following concepts as a class:
- Frictional force is the force that opposes motion between two surfaces.
- Frictional force causes negative acceleration.
- Velocity does not have an effect on frictional force.
- Acceleration measures the change of speed of an object that is moving is a specific direction.
- All objects accelerate towards the earth at 9.8 m/s2.
- Acceleration due to gravity is 9.8 m/s2.
LEARN THE LabLearner LINGO
The following list includes the one new Key Term that is introduced in the Investigation Background(s). It should be used, as appropriate, by teachers and students during everyday classroom discourse.
Note: The definitions of this term can be found on the Introduction page to the CELL.
Note: Additional words may be bolded within the Background(s). These words are not Key Terms and are strictly emphasized for exposure at this time.
SET FOR SUCCESS
- Review your findings from Investigation Two.
- Based on your experiments in Investigation Two, what is the relationship between frictional force and velocity?
- During this Investigation, you will be conducting more trials to determine whether or not two more factors influence frictional force.
- You will conduct your trials using the same method as was used in Investigations One and Two.
- During these trials, is it important that you pull the woodblock at the same velocity in each trial? No
Note: You should understand based on your conclusions after Investigation Two that frictional force does not depend on velocity. Although you had to maintain a constant velocity throughout a trial, the velocities between trials may differ slightly.
- Play the video below. Remember to follow along with your SDR and make any notes that you think might be helpful in the lab.
- After the video, divide into your lab group to discuss strategy for the lab. For example, you may assign certain group members to perform specific functions during the lab.
Note: The purpose of the video is to allow you to anticipate the laboratory experience you will soon encounter. You should leave this PreLab session with a firm idea of what to expect and how to perform in the lab.
Note: Homework is posted below the video.
You should review the Investigation and video in preparation for the Lab.