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# PreLab

### BRANCH OUT

Automotive engineers design cars so that the amount of friction between the moving parts of the engine is reduced. Less friction means less wear and tear on the engine. They also work to reduce the coefficient of friction of the car body to zero so that it can move through the air efficiently – think of a sleek race car.

### GET FOCUSED

This Investigation is designed to help you to answer the following Focus Question:

• How does the velocity of an object affect the frictional force between it and the surface with which it comes in contact?

Note: This question is located in your  SDR at the beginning and end of the Investigation.

### GO DEEPER

As a class, read the Background(s) in Investigation 1. When finished, discuss the following concepts as a class:

• A force is a kind of push or pull on an object.
• Acceleration measures the change of speed of an object that is moving in a specific direction.
• Velocity is a measure of the sped of an object that is moving in a specific direction.

### LEARN THE LabLearner LINGO

Although there are no new Key Terms introduced in the Investigation 2 Background(s), the Key Terms from Investigations 1 should continue to be used, as appropriate, by teachers and students during everyday classroom discourse.

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 velocity with your class. Remember that an object’s velocity depends on its speed and its direction.
• Recall Investigation One.
• Describe the relationship between the amount of force recorded by the spring scale when pulling the woodblock and the frictional force between the woodblock and the table
• 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.

### HOMEWORK

You should review the Investigation and video in preparation for the Lab.