Free Body Diagrams

01.

What does a free-body diagram illustrate, and how is it used?

Essential Questions

LEARNING
OBJECTIVES

Describe quantitatively and qualitatively how net force (balanced and unbalanced) affect motion

Illustrate forces acting on an object using a free-body diagram.

Let’s Summarize

Forces-

▪ There are many different forces which act on objects such friction, magnetism, and gravity

▪ If forces are balanced the object doesn’t change its motion.

What about unbalanced forces? Can you list some possibilities? (BE SPECIFIC)

Let’s Summarize

Forces-

▪ There are many different forces which act on objects such as gravity, magnetism, and friction.

▪ If forces are balanced the object doesn’t change its motion.

▪ If forces are unbalanced the object will

______________.

1. Begin to move

2.

Stop moving

3.

Change direction

4.

Speed up

5.

Slow down

Speaking Activity

We can illustrate these balanced or unbalanced forces with a
Free-Body diagram (also called a Force diagram) like the one on the
right.

• Can you name the forces at work here?
• Are they balanced or unbalanced?
• Will the object move? If so, how?

Notes

Practice or Check

The ship is floating on the water, the forces are balanced.

Which forces are acting on the ship?

Draw a “ship” and the arrows to
complete a free-body diagram.

Practice or Check

PHYSICAL SCIENCE | LESSON 7.15 | FREE-BODY DIAGRAMS

Practice or Check

The paperclip is jumping
up to the magnet.

Which forces are acting on
the magnet? Which is the
greater force?

Draw a magnet, paperclip
and the arrows to complete
a free-body diagram.

11

PHYSICAL SCIENCE | LESSON 7.15 | FREE-BODY DIAGRAMS

Practice or Check

The paperclip is jumping up to the
magnet.

The magnetic force is greater than
the force of gravity therefore the
paperclip moves in the direction of
the biggest force.

The magnetic force is
pulling the paperclip

upwards

Gravity is pulling the paperclip to the ground

12

Computer Activity

Your teacher will direct you to an interactive website to practice some more on your own!
Check and modify your answers until you get them correct.

PHYSICAL SCIENCE | LESSON 7.15 | FREE-BODY DIAGRAMS

Worksheet

14

Now that you have had the
opportunity to practice and
check your work online,
your teacher will give you a
handout to continue toward
mastery!