Module 3 Lesson 4

Module 3—Effects of Force on Velocity

Finding Net Force Using Free-Body Diagrams

Read

How do you use free-body diagrams to find the net force when there is more than one force in a particular direction? Read “Using Free-Body Diagrams to Find Net Force” on pages 131 to 133 of your textbook.

Self-Check

SC 5. Go to page 132 of your textbook and complete question 1 of "Practice Problems."

Check your work.

Self-Check Answers

SC 5.

Analysis and Solution

We will assume the vertical forces are balanced and only consider the horizontal forces, choosing the forward forces as positive.

Paraphrase

The net force on the sled is 190 N [forward].

Module 3: Lesson 4 Assignment

Remember to submit the answers to TR 1 to your teacher as part of your Module 3: Lesson 4 Assignment.

Try This

You need to have the Free-Body Drawer simulation open as you work through the following questions.

TR 1. Select “project” from the drop-down menu titled “Projects” at the top of the applet. Load the images shown below using the “Image” button (), and complete the table by doing the following:

Identify and list all of the forces in the system.
Draw a correctly labelled free-body diagram (FBD).
On your FBD, draw a convenient coordinate system and assign vector directions.
Derive the relevant net force equations for the FBD as shown above.

The first project is done for you as an example.

You may print out the FBD and coordinate axis for each project by right-clicking on the diagram and selecting Print. You will be shown a preview screen. Click on the printer icon at the bottom, and select your printer (or print to file if you are sending your answer electronically). Click OK.

Project	List Forces	Draw FBD	Equations (m1 and m2)
	normal force tension friction weight		Fnet= (+T) + (–Ff) Fnet = zero ma = zero