Science 10th grade
LEARNING UNIT
Where are we located in
time and space?
S/K
LEARNING OBJECT
What would happen if the earth stood still at this very
moment?
 Explain the law of inertia and the effect of external
forces on the state of motion in an object.
 Check the influence of the frictional force on the
motion state of a body.
 Explain
the
frictional
force
from
the
surface
characteristics of the moving object and the surface
through which it travels.
 Explore about the mechanisms that allow the
reduction of the friction force among objects.
Language
English
Socio cultural context of
the LO
Curricular axis
Colombia
Standard competencies
I can establish relationships between the forces acting on
bodies at rest or motion and Newton's laws.
It is important to have clear concepts like uniform motion,
rest, representation of forces in the Cartesian plane, force
definition, contact forces , free body diagram.
Second Conditional
Standstill:
A condition in which all movement or activity has stopped.
Seasons:
One of the four periods of the year; spring, summer,
autumn, or winter.
Mass:
A large amount of something that has no particular shape
or arrangement.
Weight:
How heavy something is when you measure it.
Sandpaper:
Strong paper covered on one side with sand or a similar
substance, used for rubbing wood in order to make the
surface smooth.
Background Knowledge
English Review topic
Vocabulary box
Living environment, science, technology and society.
Motion: the process of moving or the way that someone or
something moves.
Words
retrieved
from:
http://dictionary.cambridge.org/
NAME: _________________________________________________
GRADE: ________________________________________________
What would happen if the earth stood still at this very
moment?
•
What would happen with day and night?
•
What movements would the Earth cease to experience?
•
What do you think you could see if you were at the seaside?
•
If a rollercoaster were running, what would happen with the people
enjoying that ride?
•
Would seasons exist?
•
If the earth stood still, would there still be the concept of force present?
•
When the body is at rest, are there forces acting? And if there are forces
acting, why is there no movement?
•
And when there is movement, are these forces still at work?
Up next, we start with the development of the Learning Object.
INTRODUCTION
With the help of the teacher, see the video what would happen if the earth stood
still at this very moment? After viewing the video, answer the following questions
and record your comments in a notebook.
I invite you to develop this learning object.
OBJECTIVES
1. To explain Newton’s first law and its relationship to the state of motion
or rest of a body.
2. To identify the frictional force as a contact force that is present in the
objects found on a surface as opposed to movement.
ACTIVITY 1
LAW OF INERTIA
In the first law, called the principle of inertia, Isaac Newton establishes the
relationship between the forces acting on a body and type of motion that such
body describes. The Law of Inertia states that: "Everybody remains at rest or in
uniform motion if no force acts on it or if the net force acting on it is zero."
Retrieved from the book: Física 1. Hipertexto. Editorial Santillana.
The first part of the Law of Inertia refers to the bodies that are at rest and
establishes that they do not act on any force, or the sum of the forces acting on
them is zero. The second part of the law establishes that if a body moves with
constant speed in a straight line, then no forces act on it or the net force is zero.
Daily experience shows that a body, which describes a rectilinear movement,
stops after travelling a certain distance. This is due to the interaction with the
material medium on which it moves and which opposes the object sliding. If
such interaction did not occur, an object that describes a rectilinear movement
would continue indefinitely moving with constant speed.
How do we name the interaction between two contact surfaces, which makes
bodies stop and continue their path indefinitely?
In conclusion, bodies tend to maintain their state of motion or rest: a body at
rest seems to resist movement and a moving body resists stopping. This
tendency of bodies NOT TO CHANGE THEIR STATE OF MOVEMENT is
known as INERTIA. (Hipertexto Física 1 Santillana).
Exercise 1:
Let´s experiment!
Materials: A playing card and a coin
Procedure: Put a playing card on your thumb without dropping it, and then put
the coin on top of it.
Your challenge… consists of removing the playing card without moving the
coin.
Hypothesis: Is it possible to do that? Build a hypothesis, stating what you
think may happen and then record it in your notebook.
Result Analysis:
After carrying out the experiment, make notes on what you observed and answer
the following questions:
1. The force was applied to which object? The coin or the card?
2. The coin experienced some kind of external force. Yes___ No____
Why?
3. What happened to the coin when the card was removed?
4. Why do you think the coin did not change its resting state?
5. With your own words, explain how this experiment serves to explain
the Law of Inertia.
6. Enter the following link to know more about the Law of Inertia:
https://m.youtube.com/watch?v=FghZEOeWcWA
7. After watching the video, explain with your own words the Law of
Inertia.
ACTIVITY 2
FRICTION FORCE
The surfaces are generally not perfectly smooth and have a series of ridges that
sometimes match those of other surface, when in contact. Therefore, when you
try to move a body on a surface or when a body slides over it, THE FRICTION
FORCE, opposed to the motion appears. (Física 1 Santillana)
Did you know that…?
There are two kinds of friction forces: Static and dynamic
STATIC FRICTION FORCE:
It appears when the applied force F is exerted on a body. The frictional force Fr
balances it, since the object is stationary.
DYNAMIC FRICTION FORCE:
When the force applied to an object exceeds the frictional force in intensity, the
object moves . When the object is moving , the friction force is smaller, making
the applied force overcome the friction force to start moving.
(Movement direction)
Exercise 1
ANALYZE!
A boy pulls a sled; according to the situations answer the following questions:
1. In which surface does the sled slide with more difficulty?
a. Ice surface
b. Grass surface
2. Why do you think the sled slides with more difficulty?
a. The contact of the sled over the surfaces
b. The sled weighs more on one of the surfaces
c. None of the above
d. Other: _______________________________
3. How would you call the action making the sled to slide with more difficulty?
a. Frictional force
b. Impulse
c. Energy
d. Weight
Exercise 2
Let´s experiment!
Get togheter with your classmates.
Materials:
1. An inclined plan
2. A wheeled block to slide on the inclined plan
3. A white letter-size sheet
4. A sheet of sandpaper
5. A piece of cloth
6. Mixture of water and soap
7. A stopwatch
8. Tape
Procedure:
1. Place the inclined plan on a stable table and on the surface of the plane, put
the wheeled block (car) and let it slide on the plane, starting its trajectory
from the top. Record the time it takes to reach the lower end.
2. After that, change the plan surface with the materials required for the
experiment. Start with the white sheet and let the car slide. Record the time
it takes to reach the plan end; Repeat the procedure with the sandpaper and
cloth. At the end dampen the inclined plan with soapy water and repeat the
procedure.
Hypothesis:
Get together with your classmates and discuss about the possible results you
can obtain when doing this experience. Take into account the time the car could
take to go along the inclined plane when varying the contact surfaces. Record
this information in your notebook and then compare it with the results of the
experiment.
Data collection:
Record the times obtained during the experiment in the following data table:
SURFACE
TIME SPENT
(Seconds)
Inclined Plane
White Sheet
Sandpaper
Cloth
Soapy water
Data Analysis:
After performing the experiment and recording the times in the data table,
perform the following activities and answer the following questions:
1. Contrast your hypothesis with the results obtained and set the differences and
similarities you find.
2. In the following table, register what you feel when touching the different
textures of each surface used.
SURFACE
Inclined Plane
White Sheet
TEXTURE
Sandpaper
Cloth
3. According to the texture of each surface and the time the car took to slide
down the inclined plane, what can you conclude?
4. What surface was better for the car to slide? What is the reason to explain
the result obtained?
5. What surface was more difficult for the car to slide?
6. All surfaces have different textures, why is that?
7. According to this experience, is there a relationship between the contact
surfaces and the opposition bodies face to get moving? Explain.
8. Check the
following
link to know more about the
frictional force
https://www.youtube.com/watch?v=dieKYguzhtY
9. After watching the video and the doing the experiment, what influence is
there between the frictional force and the motion state of a body?
10. Using your own words explain how the frictional force is affected by the
surface characteristics of the moving object and the surface on which it
moves.
ACTIVITY 3:
Exercise 1
FOOD FOR THOUGHT: Answer the following questions:
1. Is it possible to run freely on an ice-skating rink?
2. What is needed to slide on the ice-skating rink?
3. Why do we need to wear special shoes on the ice-skating rink? What is
the function of those shoes from the physical point of view and from what
has been learned?
4. Would it be possible to walk on a surface if there were no friction force?
Explain your answer.
5. Why the Earth is moving even though there is no friction force interacting
with it?
6. What effect do the moon, the planets and stars produce on the Earth,
considering that even if there is no contact between their surfaces to
produce friction and thus motion, they continue to move?
7. Do you know any mechanism created by man today where there is
movement between two bodies without them having direct contact?
DID YOU KNOW THAT…?
There is movement between two bodies, which are not in contact, and this is
known as Magnetic Levitation.
1. Go to the following link to know more about the magnetic levitation and
its application today https://www.youtube.com/watch?v=Ys5Ozzrjahk
2. According to the proposed video, write how the magnetic levitation
operates by using your own words? What physical principle does it use?
3. Imagine what other applications would be given to this principle within 20
years?
4. Find out what basic physics principles are used for magnetic-levitation
trains and for planetary motion?
5. In class, share with your classmates and complete the following table:
PHYSICAL PHENOMENON
PHYSICAL PRINCIPLE
DEFINITION
Planetary motion
Magnetic Levitation
ABSTRACT
LEW OF INERTIA
In the first law, called the principle of inertia, Isaac Newton establishes the
relationship between the forces acting on a body and type of motion that body
describes. The Law of Inertia states that: "Everybody remains at rest or in
uniform motion if no force act on it or if the net force acting on it is zero. Tomado
del libro Física 1. Hipertexto. Editorial Santillana.
The first part of the Law of Inertia refers to the bodies that are at rest and
establishes that they do not act on any force, or the sum of the forces acting on
them is zero. The second part of the law establishes that if a body moves with
constant speed in a straight line, then no forces act on it or the net force is zero.
Daily experience shows that a body, which describes a rectilinear movement,
stops after travelling a certain distance. This is due to the interaction with the
material medium on which it moves and which opposes the object sliding. If
such interaction did not occur, an object that describes a rectilinear movement
would continue indefinitely moving with constant speed.
In conclusion, bodies tend to maintain their state of motion or rest: a body at
rest seems to resist movement and a moving body resists to stop. This
tendency of bodies NOT TO CHANGE THEIR STATE OF MOVEMENT is
known as INERTIA. (Hipertexto Física 1 Santillana).
FRICTION FORCE
The surfaces are generally not perfectly smooth and have a series of ridges that
sometimes match those of other surface, when in contact. Therefore, when you
try to move a body on a surface or when a body slides over it, FRICTION
FORCE, opposed to the motion appears. (Física 1 Hipertexto Santillana)
STATIC FRICTION FORCE:
It appears when the applied force F is exerted on a body. The frictional force Fr
balances it, since the object is stationary.
DYNAMIC FRICTION FORCE:
When the force applied to an object exceeds the frictional force in intensity, the
object moves . When the object is moving , the friction force is smaller, making
the applied force overcome the friction force to start moving.
MAGNETIC LEVITATION PRINCIPLE
Ii is a phenomenon happening when a given material can literally levitate thanks
to the repulsion between equal poles (repulsive action), between two magnets.
Levitation in a maglev train is produced by the interaction of magnetic fields,
which give rise to forces of attraction or repulsion.
HOMEWORK
Consider the following situations and explain with your words, the path that the
occupants of the following vehicles follow, when they experience a sudden
change in its state of motion or rest:
1. A motorcyclist who stumbles upon a stone
2. A bus full of passengers being at rest and starts moving sharply
 Why do passengers oppose to change its state of rest?
3. The driver of a moving car that changes direction abruptly.
 Why, if the driver turns right for your body experiences a slight
movement forward creating the sensation of you turning left?
Explain!
1. In these situations, is the Law of Inertia present? Justify your answer
2. Identify the frictional force on the following systems and indicate its direction
EVALUATION
1. In the following word search, find the words that correspond to the
meanings below:
a. Force that opposes motion
b. Tendency of bodies to oppose changing their state of motion or rest.
c. Physicist who established by the Law of Inertia
d. Frictional force exerted on a body and balances with the applied force,
making the object remain still.
e. When the force applied to an object exceeds in intensity the frictional
force making the object move, we are talking about frictional force.
Answers: a. friction, b. inertia, c. Newton, d. static, e. dynamic.
2. Complete the following sentences:
a.
Everybody
remains
in
______________
or
in
moving
__________________________ if any_____________ acts on it or if
the net force acting on it is __________.
b. The tendency ______to change their _____________________status
is known as ____________
c. The ______________force opposes_________________ bodies
d. There are two kinds of frictional forces; ___________________ and
____________________
e. F. _____________________ is the physicist who created the Law of
Inertia.
Answers: a. rest, uniform linear, zero. b. Not, movement, inertia. c. friction,
moving. d. static, dynamic. e. Isaac Newton
3. Locate the forces exerted on the block in the following graph and inquire
what is the meaning of μ:
y
4. Select the correct answer according to the statements:
 Contact force opposing the motion of bodies:
a. Tension
b. Friction
c. Weight
d. Magnetic
 The tendency of bodies not to change their state of motion or rest :
a. Gravity
b. Inertia
c. Friction
d. Mass
 The physicist who stated the Law of Inertia:
a. Galileo Galilei
b. Isaac Newton
c. Albert Einstein
d. Aristotle
 The Maglev uses the physical concept:
a. Magnetic field
b. Law of inertia
c. Contact forces to produce movement
d. None of the above
GLOSSARY
Friction force: Contact force that opposes the motion of bodies.
Static friction force: Frictional force acting when the bodies are at rest with
respect to the surface on which they reside.
Dynamic friction force: Frictional force acting on bodies when they are in
motion regarding the surface on which they are.
Inertia: The tendency of bodies not to change their state of motion or rest.
Law of inertia: Everybody remains at rest or in uniform motion if no force acts
on it or if the net force acting on it is zero.
Uniform rectilinear motion: Movement that is characterized by constant
speed and zero acceleration.
Movement: Position change of a particle with respect to a reference point.
Rest: A Particle lacking movement.
Constant speed: When a particle experiences neither increase nor decrease in
speed.
BIBLIOGRAPHY

Bautista Ballén, M. Salazar Suárez, F. (2011). Hipertexto Física 1. Bogotá,
Colombia: Santillana.

Hewitt, P. (1999). Física Conceptual. México: Pearson Educación.

Youtube.com (24 de marzo de 2014). Aprende sobre la Ley de la Inercia
con
los
Experimentores.
Recuperado
de:
https://m.youtube.com/watch?v=FghZEOeWcWA

Explainers.TV (15 de marzo de 2012). Trenes de levitación magnética, en
3
minutos.
Recuperado
de:
https://www.youtube.com/watch?v=Ys5Ozzrjahk

Youtube.com (30 de julio de 2014). ¿Qué podremos lograr a través de la
fricción?
Recuperado
https://www.youtube.com/watch?v=dieKYguzhtY
de: