SHS

GENERAL PHYSICS 1
Module 11, Quarter 1, Week 4
General Physics 1
Grade 11/12 Module 11 Quarter 1, Week 4
First Edition, 2020

Copyright © 2020
La Union Schools Division
Region I

All rights reserved. No part of this module may be reproduced in any form without
written permission from the copyright owners.

Development Team of the Module

Author: FRANKLIN PADILLA

Editor: SDO La Union, Learning Resource Quality Assurance Team

Illustrator: Ernesto F. Ramos Jr., P II

Management Team:

ATTY. Donato D. Balderas, Jr.

Schools Division Superintendent

Vivian Luz S. Pagatpatan, PhD

Assistant Schools Division Superintendent
German E. Flora, PhD, CID Chief

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Rominel S. Sobremonte, EdD, EPS in Charge of Science
Michael Jason D. Morales, PDO II
Claire P. Toluyen, Librarian II
 General Physics 1
Module 11: Quarter 1 – Week 4
 Target

Sir Isaac Newton place a variety of laws that describe and explain why objects
move (or don't move) as they do. These three laws have become known as Newton's
three laws of motion. These laws describe the connection between a body and the
forces acting upon it, and its motion in response to those forces.

In your previous lesson, you have just determine the how the first law of
motion (Law of Inertia) can be used to define the so called Inertial frame of reference.
Eventually, it will be the other important meaning and use of Newton’s First Law – it
is the law that defines an inertial reference frame as any frame where an object
remains in a state of uniform motion if no forces act on it.

This learning material will provide you the information and activities that will
help you understand the concept of the Third law of Motion.

At the end of this learning material, you are expected to:

1. Identify action-reaction pairs. (STEM_GP12N-Id31)

2. Solve problems using Newton’s Third Laws of motion in contexts such as,
but not limited to, ropes and pulleys, the design of mobile sculptures,
transport of loads on conveyor belts, force needed to move stalled vehicles,
determination of safe driving speeds on banked curved roads
(STEM_GP12N-Ie38)

To understand the lesson well, do the following activity on this learning material.
Enjoy learning!!!

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 Jumpstart

Activity 1: Concept Reading- The Third Law of Motion and the 2 forces
Newton's third law states, “For every action force there is an equal (in size)
and opposite (in direction) reaction force”. These forces are always come in pairs.
These pairs are known as “action-reaction force pairs." Two things must be done
in identifying and describing the two forces, one of which is to identify the two
interacting objects and conclude two statements describing who pushes on whom
and in what direction.
Study this diagram:

A person who is trying to push the wall.

Figure 1

Directions: Answer the following questions based on what you understand from the
text given: Write your answer on the space provided.

1. What are the two interacting object?

___________________________________________________________________________
2. What did the person exert on the wall?
___________________________________________________________________________
3. Do you think the wall exert also force against the person?
___________________________________________________________________________
4. Describe the force that they have exerted against each other:
___________________________________________________________________________
5. Which one gives an action force? Reaction force?
___________________________________________________________________________

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 Discover

Newton’s Third Law of Motion: INTERACTION

Consider the interaction between the bird’s
wing and the air as the two interacting bodies. The
bird’s wing pushes the air downward and as a
reaction the air pushes the wings of the bird upward
Figure 2
and as a result, the bird moves upward and had the ability to
fly.

The direction of the two forces exerted by the two bodies is in opposite
direction. Moreover, the action force that exerted by the bird is equal to the reaction
force exerted by the air. Together, these two forces exerted upon two different objects
form the action-reaction force pair.

In formula: 𝐹𝑎 = −𝐹𝑟 ; where Fa is the action force, Fr is the reaction force,

they always come in pair with equal magnitude but opposite in direction.

These two forces are called action and reaction forces and are the subject of
Newton's third law of motion.

Formally stated, Newton's third law is:

“For every action, there is an equal and opposite reaction.”

This statement means that in each interaction, there is a pair of forces acting
on the two interacting objects. The magnitude of the forces on the first object is equal
to the magnitude of the force on the second object.

The direction of the force on the first object is opposite to the direction of the
force on the second object. Forces always come in pairs - equal and opposite action-
reaction force pairs.

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 Explore

Here is an activity for you to work on for you to master

the basic concept you have learned in this lesson.

Now that you already know the action-reaction force, you are now ready to
do this activity.

What you need: pen/pencil

What to do: Identify the action-reaction force of the given example. Write
your answer on the space provided.

1. A basketball player shooting a basketball.

___________________________________________________________________________
2. Volleyball player hitting volleyball.
___________________________________________________________________________
3. A bike tire pushes the sown the ground.
___________________________________________________________________________
4. A rocket pushes hot air down and out, so that it takes off.
___________________________________________________________________________
5. A person (85kg) standing on a desk.
___________________________________________________________________________

Enrichment Activity 2:

What you need: pen/pencil

What to do: Identify the action-reaction force of the given example. Write
your answer on the space provided.

1. While driving down the road, a firefly strikes the windshield of a bus and
makes a quite obvious mess in front of the face of the driver. This is a clear
case of Newton's third law of motion. The firefly hit the bus and the bus hits
the firefly. Which of the two forces is greater: the force on the firefly or the
force on the bus?

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 Deepen

At this point you are now ready for your last activity. Remember the things
that you learned in this lesson. Good luck!!!

What you need: pen and paper

What to do: Your task is to give 10 samples of Action-reaction force that you have
experienced the whole day beginning the first activity after waking up in the morning.
Identify What type of force are present between the two interacting bodies in each
situation. Follow format below:

Situation/Interacting
Action force Reaction Force
Bodies

Gauge

Directions: Read carefully each item. Use a separate sheet for your answer.
Write only the letter of the correct answer.
1. What causes the inability of a rocket to provide propulsion?
A. Space is void of air so the rockets have nothing to push off of.
B. Gravity is absent in space.
C. Space is void of air and so there is no air resistance in space.
D. Rockets do accelerate in space and have been able to do so for a long
time.
2. How do forces act?
A. alone
B. in pairs
C. in one direction
D. independent from each other
3. What force does a book on a table exert?
A. a reaction force
B. an upward force
C. a downward force
D. a force in the same direction
4. For every action force, there is an equal and opposite ____ force.
A. upward
B. reaction

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 C. downward
D. the same direction
5. When a FUTSAL ball is kicked, the 2 forces (action-reaction forces) do not
cancel
each other out because
A. the forces are not equal in size.
B. the forces act on different objects.
C. the forces act at different times.
D. all of the above
6. A woman weighing 500 N sits on the floor. She exerts a force on the
floor of
A. 1000 N.
B. 500 N.
C. 250 N.
D. 50 N.
7. As a 500 N woman sits on the floor, the floor exerts a force on her of
A. 1000 N.
B. 500 N.
C. 250 N.
D. 50 N.
8. Forces always occur
A. when velocities are constant.
B. as single quantities.
C. in pairs.
D. in triplets
9. If a horse pulls on a wagon at rest, the wagon pulls back equally as much on
the horse. Will the wagon be set into motion?
A. No, because the forces cancel each other.
B. Yes, because there is a net force acting on the wagon.
C. Yes, because there is a time delay between action and reaction.
D. Yes, because the horse’s pull on the wagon is larger than the wagon’s
pull on the horse.
10. A high school student hits a nail with a hammer. During the collision, there
is a force
A. on the hammer but not on the nail.
B. on the nail but not on the hammer.
C. on the nail and also on the hammer
D. all of the above

True or False Questions

Write True if the statement is correct and False if gives incorrect information
______ 1. Whenever one object exerts a force on a second object, the second
object always exerts the same amount of force back on the first
object.
______ 2. A rocket ship is pushed forward by gases that are forced out the
back of the ship.
______ 3. In order to make a cart move forward, a horse must pull harder on
the cart than the cart pulls on the horse.
______ 4. If a bicycle and a parked car have a head-on collision, the force of
impact is greater on the bicycle.
______ 5. The earth and moon pull on each other with equal amounts of
force

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References:

Printed Material

K to 12 basic education curriculum Senior high school – science, technology,

engineering and mathematics (stem) specialized subject. General Physics 1.
List of Learning Competencies

General Physics 1. , March 2, 2015 Open Stax College. Vibal Interactive e-Book.
Philippine Edition

Science Learner’s Material, Grade 10. Department of Education. Republic of the

Philippines.K-12 Curriculum

Website:

Action and Reaction Forces: Law & Examples. Retreived from

https://study.com/academy/practice/quiz-worksheet-action-reaction-
forces.html on July 21, 2020

Newton’s Third Law of Motion. https://www.svsd410.org/cms/lib/

WA01919490/Centricity/Domain/1355/3%20Newtons%20Third%20Law%2
0of%20Mo on.pdf

Forces and Changes in Motion. Introduction to dynamics Canadian

Academy.Retrieved from Kobehttps://www.slideshare.net/gurustip/forces-
changes-in-motion

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