Grade 8 Learner Material

1. Forces on objects
at rest
Activity No. 1

2. Objectives:
• After performing this activity, you should be able to identify the
forces acting on an object at rest.

3. Materials:
• Pen
• pair of scissors
• string
• Book
• Table

4. Procedure: (situation 1)
1. Hang a pen by a piece of string as shown in
Figure 3a.
Q1. Is the pen at rest or in motion?
.
The pen is at rest

5. Procedure: (situation 1)
1. Hang a pen by a piece of string as shown in
Figure 3a.
Q2. Are there forces acting on the pen? If yes,
draw the forces. You may use arrows to
represent these forces.
Tension
Force
Gravitational
Force
Yes. The forces acting on the pen are the
tension force (the force exerted by the string
on the pen) and the force of gravity.

6. Procedure: (situation 1)
2. Cut the string with a pair of scissors.
Q3. What happens to the pen? What could
have caused the pen’s motion? Tension
Force
Gravitational
Force
When the string was cut, the pen falls to the
ground. The force of gravity makes the
object fall down.

7. Procedure: (situation 2)
1. Place a book on top of a table as shown in
Figure 3b.
Q4. Is the book at rest or in motion?
The book is at rest.

8. Procedure: (situation 2)
1. Place a book on top of a table as shown in Figure 3b.
Q5. Are there forces acting on the book? If yes, draw the forces acting
on the book.
Yes. The forces acting on the
book are the force exerted by the
table on the book and the force
of gravity.

9. Procedure: (situation 2)
2. Let one member of your group push the book in one direction and
another member push it in the opposite direction at the same time with
the same amount of push (force).
Q6. Did the book move? How will you make the book move?
No, the book
stays at rest. The
book may be
moved by
pushing it on one
side only