Power point presentation for the subject science under the grade level 8

1. FORCES AND
MOTION

2. A push or pull on a body is called
force.
Forces is used in our everyday actions
like pushing,pulling,lifting,stretching,
twisting and pressing.
FORCE

3. • A force can move a stationary body.
A force can stop a moving body.
A force can change the speed of a
moving body.
A force can change the direction of a
moving body.
A force can change the shape and size
of a body.
EFFECT OF FORCE

4. What makes an objects move the
way they do?
Why do objects move in
different ways?
Why are some objects faster
than the others?
What makes objects stay in
place?

6. FORCE
- push or a pull that can make an
object moves.
- can make object moves faster,
stop or change in their direction of
motion.
-describe in terms of the properties
such as magnitude, direction, point
of application and line of action.

7. Magnitude – refers to the size or
strength of the force. Newton (N)
Direction of the arrow – direction of the
force
Length of the arrow – represents the
relative magnitude of the force.
Line of action – the straight line passing
through the point of application.
Point of application – is parallel to the
direction of the force.

8. - If an object stays at rest, there are forces
acting upon it.
- Hanging objects have tension forces and
force of gravity acting on them.
- Objects at rest have normal force and force
of gravity acting on them.
- Tension force is the force exerted by the
string on the object.
- Normal force is the upward force
perpendicular to the surface of contact
between two bodies.

9. Activity 1 FORCES ON OBJECTS AT REST
Materials: Pen string pair of scissors books
PROCEDURE: Situation 1
1.Hang a pen by a piece of string as shown in the figure
2.Cut the string with a pair of scissors.
PROCEDURE: Situation 2
1.Place a book on top of a table as shown in the figure.
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)

10. QUESTIONS
1.Is the pen at rest or in motion?
2.Are there forces acting on the pen? If yes, draw the
forces . You may use arrows to represent these forces.
3.What happens to the pen? What could have it caused
the pen’s in motion?
4.Is the book ate rest or in motion?
5.Are there forces acting on the book? If yes, draw the
forces acting on the book.
6.Did the book move? How will you make the book
move?

11. BALANCED – when the net force
on an object equals to zero. These
do not produce change in motion.
UNBALANCED – when the net
force on an object is not zero.
These produce a change in motion.
BALANCED VS.UNBALANCED
FORCES

12. BALANCED
– the forces acting on an object are
equal in magnitude but opposite in
direction.
–lie along the same line of action.
–the object either stays at rest or
continues to move at constant
velocity.

13. FRICTION
– acts opposite the direction of
motion.
–slows down/resists the motion of an
object.
Due to unbalanced force, the object
change its state of motion hence we
say that it accelerates or increase in
velocity but it can also decelerate or
decreases in velocity.

14. UNBALANCED FORCE
– The motion of the object will
change.

20. Activity 1 FORCES ON OBJECTS AT REST
Materials: Pen string pair of scissors books
PROCEDURE: Situation 1
1.Hang a pen by a piece of string as shown in the figure
2.Cut the string with a pair of scissors.
PROCEDURE: Situation 2
1.Place a book on top of a table as shown in the figure.
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)

21. QUESTIONS
1.Is the pen at rest or in motion?
2.Are there forces acting on the pen? If yes, draw the
forces . You may use arrows to represent these forces.
3.What happens to the pen? What could have it caused
the pen’s in motion?
4.Is the book ate rest or in motion?
5.Are there forces acting on the book? If yes, draw the
forces acting on the book.
6.Did the book move? How will you make the book
move?