effects of forces

1. Learner’s book p. 122
Workbook book p. 62,63

2. Something that
cause an object
moves, changes its
speed, direction
and shape.
In science,
force, usually
means either a
push or a pull

3. B
A
D
J
F
H
I
C
G
E
K
L

4. We cannot see forces.
We can measure them and sometimes feel
the effects they have on things.
Forces are measured in newtons (N)
Some Types of Force
Gravity
Weight

5. The force of gravity also exists on the Moon
but it is not as strong as it is on the Earth.
This is because the Moon is much smaller than
the Earth.

7. Gravity is a force that pulls objects
downwards towards the centre of the
earth

8. Mass : the amount of matter it contains
It is measured in grams (g) or kilograms (kg)
but it is NOT a force.
Weight : the force caused by gravity
pulling down on the mass of an
object.
It is measured in newtons (N).

9. No Objects Mass
(g)
Weight
(N)
1 I 100 1
2 II 200 2
3 III 300 3
4 IV 400 4

10. 0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
100 200 300 400
Weight
(N)
Mass (g)

11. 1. if the mass of an object is 560 grams,
then how is it weight?
2. if the weight of an object is 5 N, what is
the mass of the object?

12. Friction is the resistance between two
surfaces that are in contact with each
other.

14. Air resistance pushes against things which
are moving.

15. To cut through
the wind

16. Upthrust is the force that pushes an
object up and makes it seem to lose weight
in a fluid. (Remember, a fluid means a
liquid or a gas)

17. When a force work on an object, there
always another force that work on it from
the opposite site.
e.g:

19. Mass is the amount of matter it contains
Weight is the size of the force of the gravity
depends on the object’s mass and its distance
from the object it’s attracting.

20. We measure force in newtons. We use
an instrument called a spring balance
known as a force meter or a newton
meter.

21. I. Aim: Find out the different of force in the
air and in the water
II. Tools and materials
Forcemeter
Objects that sink in water (glass, plasticin,
metal)
water
Jar

22. I predict that the weight of the object in the
air will be _(higher than, lower than or
equal to) _ the weight of the object in
water. If I put more water into the beaker, I
predict that the reading on the Newton
meter will __(increase, decrease, or not be
any different to before)

23. Attach an object to the forcemeter
Check the force needed to lift it in the air
Put the object on the water in the jar and
make sure that its not touch the bottom of
the jar
Record your data in a table
Repeat your measurement for 3 times
Do the same thing to other objects

24. No.
Weight in
the air
(N)
Weight in the
water
(N)
Upthrust on
object
(N)
I 4 0.5 4 – 0.5 = 3.5 N
II 4 1.5 4 – 1.5 = 2.5 N
III 4 1 4 – 1 = 3 N
Average 3 N
1. Plasticine

25. No.
Weight in
the air
(N)
Weight in the
water
(N)
Upthrust on
object
(N)
I 2 1.5 2 – 1.5 = 0.5 N
II 2 1.7 2 – 1.7 = 0.3 N
III 2 1.7 2 – 1.7 = 0.3 N
Average 0.37 N
2. Metal

26. Is there any different when you measure
the weight in the air and in the
water?_____
Tell the difference___________
What type of force that occurs in this
experiment?