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PL AR RS P6L2 Interaction of Forces II WS

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PL AR RS P6L2 Interaction of Forces II WS

PL AR RS P6L2 Interaction of Forces II WS

Primary 6

Rocket Science

Name Interaction of Forces II (Lesson 2)
Tutor

Topic Interaction of Forces II (Lesson 2)

Primary 6: Rocket Science

Friction

Friction is a force that exists between surfaces that are rubbing against each other.
• Friction opposes motion

• Friction acts to reduce the speed of a moving object.
• Friction acts in the direction opposite to the direction in which the object is

moving.

• Friction produces heat.

• Friction between rougher surfaces is greater and produces more heat than

friction

between smoother surfaces.

• Friction is useful as it reduces slipping and sliding Lesson

• It can also be a problem as it causes wear and tear, overheat things and make

objects

move slowly.
• To overcome friction, lubricants like oil or grease can be used on moving parts of

machines. Rollers and wheels can be used to help move large objects. Living

things have streamlined body to overcome friction when moving in air or water.

Elastic spring force

AR Model –Spring
• Elastic objects change shape when a force acts on them, but they return to
their original shape once the force is removed.
•When an elastic object is stretched or compressed, it exerts a force on the object
stretching or compressing it. This force is called elastic spring force.
•Springs are elastic. Pulling on a spring causes it to stretch while pushing on a
spring causes it to compress.

2

Primary 6: Rocket Science

Gravitational force

Gravity is the force of attraction that exists between things that have mass.

Gravity depends on:
• The mass of the objects
• The distance between the objects
• When we refer to an object’s gravity, we usually mean the force between

the Earth and the object. Our Earth has a very large mass, which is why
it exerts a very large gravitational pull

Lesson

Magnetic force

• Magnetic force is responsible for the action of magnets on magnetic materials.

There are two types of magnetic force. The magnetic force of attraction and
repulsion.

AR Model – Magnetic Field

3

Primary 6: Rocket Science

Instructions to learners

Complete the 4 activities in this lesson package.
• Activity 1 – Movement on different surfaces
• Activity 2 – Completing 10 multiple choice questions assigned
• Activity 3 – Completing and submitting 2 open-ended questions
• Activity 4 – Discussing the concepts in the Fun Facts Video

4

Primary 6: Rocket Science

Activity 1 – Movement on different surfaces
Objective: To determine how the texture of a surface affects distance travelled by a
ball or a wound up toy car.

Discussion:
On which surface will the toy car move the furthest?
On a surface like thick grass the toy car might not even move.
Why?
Notes:

5

Primary 6: Rocket Science

3. Friction is a problem when .

A: A lot of unwanted heat is produced.
B: It causes our shoes to wear out.
C: Machines need extra energy to overcome it.

(1) A and B only (2) A and C only
(3) B and C only (4) A, B and C

()

4. The table below shows the forces present when activities, X and Y, are carried out.

Activity Frictional Force Magnetic Force Gravitational Force
X Yes No Yes
Y Yes Yes Yes

Based on the table above, which of the following correctly describes activities X
and Y?

Activity X Activity Y

(1) Rolling a ball down a ramp. Placing a plastic rod beside a bar
magnet.

(2) Holding a compass in the hand to Rolling a ball down a ramp.
tell direction.

(3) Leaning a book against the Pushing an iron rod towards a bar
bookshelf. magnet.

(4) Holding a compass in the hand to Placing a plastic rod beside a bar
tell direction. magnet.

()

6

Primary 6: Rocket Science

7. What is the force that causes the trolley to move down the slope by itself?

(1) The force of attraction between the Earth and the slope.
(2) The force of attraction between the Earth and the trolley
(3) The force of attraction between the Slope and the trolley
(4) The frictional force between the trolley and the slope

()

8. What will the effect be when a man pulls a trolley?

(1) The force exerted by the man will change the earth’s gravitational force
that is acting on the moving trolley.
(2) The force exerted by the man will change the mass of the moving trolley.
(3) The force exerted by the man will increase the speed of the trolley.
(4)The force exerted by the man will slow or stop the movement of the
trolley.

()

7

Primary 6: Rocket Science

9. Caleb conducted an experiment using springs A and B. He attached weights one
at a time and recorded the length of the spring. The results are shown in the graph
below.

Which one of the following correctly matches the springs to the observations that

Length of spring is shorter at the Spring can be extended longer
start of experiment with the same amount of weight

(1) A B

(2) B A

(3) A A

(4) B B

()

8

Primary 6: Rocket Science

10. The diagram below shows how a toy rocket moved after it has blasted off from the
ground

Which of the following statement(s) is/are true?

A Gravity causes the toy rocket to move away from the ground.
B Gravity causes the toy rocket to change direction from its original path.
C Gravity slows down the toy rocket as it moves away from the ground

and pulls it back down to the ground.

(1) A only
(2) B only
(3) A and C only
(4) B and C only

()

9

Primary 6: Rocket Science

Activity 3 – Question 1
Sam dropped a ball from the top of a building as shown in the diagram below.

(a) In the diagram above, draw an arrow to show the path of the ball when it was
dropped form Sam’s hand. [1]

(b) Give a reason why the ball dropped in the direction shown in part (a). [1]

(c) Sam weighed the same ball when he was on the ground level of the building.
Would the weight of the ball change? Give a reason for your answer. [1]

10

Primary 6: Rocket Science

Activity 4 – Question 2
Hafiz studied four types of springs A, B, C and D using a set-up. His results are shown
in the graph below.

a) Which set-up did Peter use to study the four springs? Put a tick ( ) in the
correct
box. [1]

c) Explain why it is important to include the pin in the set-up. [1]

11

Primary 6: Rocket Science

Activity 4 – Fun Facts about Forces

Discussion:
What is the difference between mass and gravity?
To read up more go to: https://spaceplace.nasa.gov/what-is-
gravity/en/#:~:text=Objects%20with%20more%20mass%20have,comes%20from%20a

ll%20its%20mass.

12

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