Download Force - Kuropas 7-4 science

How can the motion of an object can
be described?
• When an object changes position over time relative to a
reference point, the object is in motion
– Motion of an object
• Always judged with respect to some other object or
point
How can the motion of an object can
be described?
• When an object changes position over time relative to a
reference point, the object is in motion
– Motion of an object
• Can be described with a reference direction
– North
– South
– East
– West
– up or down
How can the motion of an object can
be described?
• When an object changes position over time relative to a
reference point, the object is in motion
– Speed of an object
• Measure of how quickly the object gets from one place
to another
How can the motion of an object can
be described?
• When an object changes position over time relative to a
reference point, the object is in motion
– All motion is relative
• Frame of reference chosen
• There is no motionless frame from which we can judge
all motion
Graphing Changes in Motion
• Describing the motion of an object is
occasionally hard to do with words.
– Graphs help make motion easier to picture, and
therefore understand.
– Remember:
• Motion is a change in position measured by distance and
time.
• Speed tells us the rate at which an object moves.
• Velocity tells the speed and direction of a moving object.
• Acceleration tells us the rate speed or direction changes.
Graphing Changes in Motion
Graphing Changes in Motion
Graphing Changes in Motion
Graphing Changes in Motion
Graphing Changes in Motion
Graphing Changes in Motion
Science Thought 8/29
What causes
acceleration?
A force applied to
an object.
Describing Motion Objectives
• Explain how the motion of an object can
be described by its position, direction of
motion, and speed in regard to some
other object
• Illustrate the motion of an object using a
graph to show a change in position over a
period of time. Interpret distance versus
time graphs for constant speed and
variable motion.
Today’s class
• Get together in group to discuss the
questions from the test given on Friday.
Submit ONE paper for the group with
the group’s correct answers. (Put
everyone’s first and last name on the
paper.)
• Take test home and have parents sign in
order to take retest on Wednesday in
class.
Balanced and Unbalanced Forces
objective:
Explain the effects of
balanced and unbalanced
forces acting on an object
(including friction, gravity
and magnets)
https://www.brainpop.com/science/motionsforcesandtime/force/
(3 min)
When you ride a bike, your foot pushes against
the pedal. The push makes
the wheels of the bike move.
When you drop something, it is pulled to the
ground by gravity.
A PUSH or a PULL is a FORCE. So, a good
definition for force is a push or pull in a
particular direction.
Forces affect how objects move. They may cause
motion; they may also slow, stop, or change the
direction of motion of an object that is already
moving
What is a force?
•In science, a force is a push or a pull.
•All forces have two properties:
Direction and Size (use VECTOR)
•A newton (N) is the unit that
describes the size of a force.
Science Thought 8/30
What is a force and why do
we use a vector to show one?
A force is a push or pull and
the vector shows the size and
direction of the force.
What is a force?
•In science, a force is a push or a pull.
•All forces have two properties:
Direction and Size (use VECTOR)
•A newton (N) is the unit that
describes the size of a force.
https://www.brainpop.com/science/motionsforcesandtime/force/
(3 min)
Today’s class
• Notes on forces (entry # 34)
• RETEST on describing motion during
class on Wednesday
• Need original test signed by parent if
under 80
• After the retest – book work – must be
completed for Friday notebook check!
Forces can affect motion in several ways:
→ They can make objects start moving
→ They can make objects move faster
→ They can make objects move slower
→ They can make objects stop moving
→ They can make objects change direction
→ They can make objects change shape
What is a force
•The student is pushing
down on the chair,
but the chair does not
move.
•The floor is balancing
the force by pushing
on the chair.
Balanced Forces
•When the forces on an
object produce a net
force of 0 N, the forces
are balanced.
•There is no change in
the motion of the
object.
Since force cause changes in the
speed or direction of an object,
we can say that forces cause
changes in velocity, so.... Forces
cause acceleration!
Acceleration
Measures the change in an
object’s velocity over time
(Time it takes to change speed)
Units include a distance and a time
squared
Ex: mi/hr2, m/s2
Types of Acceleration:
Same Direction of Motion AKA “Speeding Up”
+
=
A force is applied in the same direction causing
the bike to speed up.
Forces in the Same Direction
•When forces are
applied in the
same direction,
they are added to
determine the
size of the net
force.
Types of Acceleration:
Opposite Direction of Motion AKA “Slowing
Down”
+
=
A force is applied in the opposite direction
causing the bike to slow down.
Forces in Different Directions
•When two forces act in
opposite directions,
you subtract the
smaller force from the
larger force to
determine the net
force.
•The net force will be in
the same direction as
the larger force.
Types of Acceleration:
At angle to motion AKA “Turning”
+
=
A force is applied at an angle causing the bike to
change direction. The speed may not change!
FORCE FACTS:
→ Forces are measured in Newtons (N)
→ Forces usually act in pairs
→ Forces act in a particular direction
→ Forces usually cannot be seen, but
their effects can
Combining Forces
•More than one force often acts on an
object.
•When all the forces acting on an object
are added together, you determine the
net force on the object.
•An object with a net force more than 0 N
on it will change its state of motion.
Net Forces
More than one force can act on an
object at a time. The forces can push
or pull in any direction.
What happens to the object when
the forces act depends on two things:
→ How strong the forces are
→ The direction of the forces
Unbalanced Forces
•When
the net force on
an object is not 0 N,
the forces on the
object are
unbalanced.
•Unbalanced forces
produce a change in
motion of an object.
In summary!
If the effects of the forces don't cancel each other, if
one force is stronger than others, the forces are
unbalanced forces. Unbalanced forces cause a
change in motion; speed and/or direction.
• When two forces act in the same direction on an
object, the net force is equal to the sum of the
two forces.
• When two unequal forces act in opposite
directions on an object, the net force is the
difference of the two forces
The final force and its direction are called a
resultant.
Science Thoughts 8/31
What happens when there
are unbalanced forces
acting on an object?
The object moves
Today in class
• Retest for describing motion
–Go to my page of the team website
–Click on the link
–Complete then submit the test
• Complete bookwork – sections 2.1&2.2
• Thurs – more notes
• Fri – Bill Nye video, quiz and INB check
Science Thoughts 9/1
What is net force?
Combining all the forces
acting on a object.
(add same direction,
subtract opposite direction)
How do balanced and unbalanced
forces affect an object?
• An unbalanced force that acts on an object changes its speed
or direction of motion, or both.
– Newton’s law
• Inertia
– Tendency of objects to
resist any change in
motion
– Reason a moving object
stays in motion with the
same velocity unless a
force changes its speed or
direction or both.
What is inertia?
Inertia is the resistance of any physical
object to any change in its state of
motion, including changes to its speed
and direction.
Inertia tells us the we need a force to get
an object to move or stop an object from
moving.
How do balanced and unbalanced
forces affect an object?
• An unbalanced force that acts on an object changes its speed
or direction of motion, or both.
– Newton’s law
• An object will not start moving until a force acts upon it
• An object will stay in motion forever unless an
unbalanced force acts upon it
How do balanced and unbalanced
forces affect an object?
• An unbalanced force that acts on an object changes its speed
or direction of motion, or both.
– Change in motion (direction or speed) of an object is
• Proportional to the applied force
• Inversely proportional to the mass.
How do balanced and unbalanced
forces affect an object?
• An unbalanced force that acts on an object changes its speed
or direction of motion, or both.
– Change in motion (direction or speed) of an object is
• Proportional to the applied force
• Inversely proportional to the mass.
Exploring Forces
We will look at three examples
of forces:
- Friction
- Gravity
- Magnets
How do balanced and unbalanced
forces affect an object?
• An unbalanced force that acts on an object changes its speed
or direction of motion, or both.
– Friction
• Force that opposes motion
• Between two surfaces that are in contact
• Amount depends on factors
– Roughness of the surfaces
– Force pushing the surfaces together
Friction
•Friction is the force that opposes the
motion between two surfaces that
touch.
•The surface of any object is rough.
•Even an object that feels smooth is
covered with tiny hills and valleys.
•The contact between the hills of
valleys of two surfaces causes them to
stick, resulting in friction.
Friction
•The amount of friction depends on:
–Roughness of the surfaces
–Force pushing the surfaces together
Types of Friction
Kinetic friction occurs when force is applied
to an object and the object moves.
Examples:
Sliding Friction: pushing an object across a
surface
Rolling Friction: between wheels and a
surface
Fluid Friction: opposes the motion of
objects traveling through a fluid (air or water)
Types of Friction
Static friction occurs when force
applied to an object does not cause
the object to move.
Reducing Friction
•To reduce the amount of friction,
apply a lubricant between two
surfaces.
Ex) Motor oil, wax, and grease
•Friction can also be reduced by
rolling, rather than pushing, an
object.
Increasing Friction
● Friction increases
● when the surface area of an object
increases.
● as surfaces are made rougher.
● when the force between two objects
increases.
Gravity
Gravity is the force of attraction
between matter.
Gravity depends on:
mass and distance
How do balanced and unbalanced
forces affect an object?
• An unbalanced force that acts on an object changes its speed
or direction of motion, or both.
– Newton’s law
• Describes the relationship between
– Gravitational force
– Mass
– Distance
Mass and Gravity
The more massive an
object the more it
can attract objects
to itself.
For example, the Sun
has a larger
gravitational effect
than the Earth.
Distance and Gravity
The further away
objects get from one
another, the less
gravitational
attraction can be
found.
https://www.brainpop.com/science/motionsfor
cesandtime/gravity/
(2:43)
Magnets
A magnet is an
object with a north
and south pole
that produces a
magnetic field and
exerts a magnetic
force.
Magnets
A magnetic field is the force field that
surrounds the magnet.
A magnetic force can cause objects to
attract or repel without needing to touch
the magnet!
Poles
Like poles will repel or move
away from one another.
Opposite poles will attract or
move towards one
another.
https://www.brainpop.com/sci
ence/motionsforcesandtime
/magnetism/
Compass
A compass uses the
Earth’s magnetic field
and magnets to help a
person determine
direction. The
magnet’s poles will
line up with the
Earth’s north
magnetic pole and
south magnetic pole.
Science Thoughts 9/2
What is the difference
between kinetic friction and
static friction?
Friction – force that keeps
object from moving
Kinetic – objects move
Static – objects don’t move
Today in class
• Quiz
• Net Force/Vectors worksheets
(#37)
• Study Jams (#38)
– Complete activity (video & quiz)
– While score on screen – raise hand so I can
sign that you have completed
– Continue to next activity
• KE and PE Nerd Words (#39)
Science Thoughts 9/6
What is inertia?
An object’s resistance
to change of motion
Sept 6 in class
both of these sites are on the team
web page (science weebly)
must be completed for homework if
not finished in class
1. Complete Study Jams
– Get each of the 5 quizzes signed – leave score on
screen until I sign (not simple machines)
2. Complete Forces and Motion
– Get quiz score signed – fill in chart and questions
Science Thoughts 9/7
What is gravity and what 2
factors effect its strength?
Gravity is the attraction
between 2 objects and
effected by mass and
distance.
Sept 7 in class
Log into Discovery Education
–Username: wcp and lunch #
Password: lunch #​
–Complete "Slippery Slope" exploration
–Fill in data chart and answer questions on
worksheet
–Any work not completed in class must be
completed for homework
Science Thoughts 9/8
What causes friction?
Contact between
surfaces – the rougher
the surface – the more
friction.
Sept 8 in class
Log into Discovery Education
– Username: wcp and lunch #
Password: lunch #​
– Complete “Magnets" exploration
•
•
•
•
•
Mad about magnets (read and timeline)
Everyday use of magnets (video and list) * real world
What is a magnet (use vocabulary list)
Animal magnetism (video and list) *physical science
Attraction is mutual (exploration, data, question)
– Watch Real World Science: Magnetism (15:42 min)
– Watch Physical Science: Magnetism (20 min)
– Complete at home
Science Thoughts 9/9
In our labs this week, why did
the car/block go farther when
it started higher on the ramp?
Had more potential energy
that converted to kinetic
energy.
Sept 9 in class
• Finish all labs
–Study jams
–Friction and motion
–Slippery slope
–Magnets webquest
–Watch 2 magnets videos (15 minutes
and 20 minutes)
Science Thoughts 9/12
What is energy?
The ability to do
work. (in physics –
work is movement)
Modeling Kinetic and Potential Energy
Explain how kinetic and potential energy
contribute to the mechanical energy of an
object. Explain how energy can be
transformed from one form to another
(specifically potential and kinetic) using a
model or a diagram of a moving object
(roller coaster, pendulum, or cars on ramps
as examples).
9/12 in class
Complete the guided notes using the power
point that follows.
Science Thoughts 9/13
How can energy be
transformed between
systems? Give an example.
Changes to be used and
passed to the next need.
How do kinetic and potential energy contribute
to the mechanical energy of an object?
• An object that possesses mechanical energy
is able to do work.
– Mechanical energy
• Possessed by an object due to its
–Motion
–Stored energy of position
Energy Transfer Objective
Recognize that energy can be
transferred from one system to
another when two objects push or pull
on each other over a distance (work)
and electrical circuits require a
complete loop through which an
electric current can pass.
Getting started
What do you already
know?
(KWL, true/false)
Reading
• Read and annotate 3 page
article.
• Review true/false and make
the false ones true based on
the information in the reading.
Science Thoughts 9/14
Why is electricity in a
circuit a force?
Electrons are being
pushed and/or pulled
through a circuit.
LAB DAY
• 3 circuit kits to be completed.
• 15 minutes per kit.
• Finish all of the activities on
the instruction sheet.
• Everyone gets a turn.
Science Thoughts 9/15
What is needed for
electricity to be useful in
our homes and for our
appliances and devices?
A Circuit
How can energy be transformed from
one form to another?
The workings of the universe plus
all of present day technology can
be viewed from the perspective of
energy flowing from one place to
another and changing back and
forth from one form to another.
How can energy be transformed from
one form to another?
• Energy appears in
different forms such as
motion and heat
• Energy can travel in
different forms, such as
light, sound or
electricity
How is energy transferred from one
system to another?
Energy is one of the fundamental
building blocks of our universe.
–Energy can be transferred from a
system to its environment
• Thermal - A warmer object is
in contact with a cooler one
• Mechanical - Two objects push
or pull on each other over a
distance
How is energy transferred from one
system to another?
• Energy is one of the fundamental building blocks of our
universe.
– Energy can change from one form to another
• Some energy is always converted to heat
• Some systems transform energy with less loss of heat
than others
How is energy transferred from one
system to another?
– Energy can be transferred from a
system to its environment
• Electrical
–An electrical source (for
example, a battery or
generator) is connected in a
complete circuit to an
electrical device
• Electromagnetic Waves (light,
heat, UV, X-rays, etc.)
How is energy transferred from one
system to another?
– Electrical energy
• Produced from a variety of energy sources
• Can be transformed into almost any other
form of energy
• Batteries
–Store energy
–Transfer energy to components in a
circuit
–Energy comes from chemical reactions
How is energy transferred from one
system to another?
– Electrical energy
• Important because we can use it
to make so many things work
–A bulb converts it into light
energy
–A speaker converts it into
sound energy
How is energy transferred from one
system to another?
– Electrical energy
• Primary source of electrical energy is the
heat generated by
–Burning fossil fuels
–Water power
–Wind power
How is energy transferred
from one system to another?
– Electrical energy
• Secondary sources of
energy
–Windmills
–Waterfalls
–Power plants
• A natural form =
lightning
How is energy transferred from one
system to another?
–Green energy
• Solar
• Water
• Wind
• Does not pollute
the environment
Reading
Complete the two reading assignments
Science Thoughts 9/16
What is green energy?
Energy that does not
harm the environment.
Circuit Lab
• Answers to yesterday’s reading (1 – AAB, 2 – DDA)
• https://www.brainpop.com/science/energy/electriccircuits/
•
•
•
•
Draw FIVE circuits
Build FIVE circuits
Write up lab observations/answer questions
Remember – lab is written as SERIES CIRCUIT but
we are also doing parallel (additional questions)
– 8. Compare brightness of lights in series circuit to
parallel circuit
– 9. What happened when the circuit was set up in
formation 4? Formation 5? Why?
Science Thought 9/19
What is the difference between
a series circuit and a parallel
circuit?
A series circuit has 2 or more
loads on the same “loop” while
a parallel circuit has a separate
loop for each load.
UNIT TEST
• Balance and Unbalanced Forces
–Net forces
–Gravity, friction, magnets
• Potential and Kinetic Energy
• Energy Transformation and
Electric Circuits
Balanced and Unbalanced Forces
a force is a
push or a pull
forces have two properties:
direction and size (use VECTOR)
forces can affect motion in several ways:
faster, start, slower, stop, change direction
Net forces:
add if same direction
subtract if different directions
Newton’s Laws
First
inertia – oppose change
(not moving – stay not moving, moving – stay moving)
Second
force = mass * acceleration
(Proportional and inversely proportional)
Third
equal and opposite force
(for every action there is an opposite and equal reaction)
Friction
Force that opposes motion
Objects in contact with each other
2 factors effect amount of friction
roughness of surface
force pushing objects together
2 types
kinetic – rolling, sliding, fluid
static – no movement
Increases with
more force, more surface, rougher surface
Lab answers
• Forces and Motion
• More friction – less distance
• More mass – less distance
• Big parachute – less distance
• Slippery Slope
• Steel & steel went farther – less friction
• Slide into base to stop faster – on base
Gravity
the force of attraction between
two objects
depends on:
mass and distance
In a vacuum – no resistance so all
objects fall at the same rate
Magnets
Objects with north and south pole
Magnetic field surrounding
Force strongest
At poles
Like poles repel
Unlike poles attract
Magnets Lab answers
• Magnetic field surrounds magnet – attract and
repel without touching
• Magnets strongest at poles
• North up for all three – all attract
• North – south – north – all repel
• South – north – north – repel and attract
• Conclusion –
– Opposites attract and same repels
Energy
• The ability to do work
• What is work?
– Cause object to move
• Mechanical - movement
– Kinetic – movement
– Potential – stored
• Transferred from one object to another
• Transformed from one type to another
Electricity and Circuits
• Electricity is a force because –
– Electrons being pushed and pulled through circuit
• Two things needed for electricity to be used –
– Current (steady) and circuit (path to travel)
• Circuit
– Power source, load, switch, conductor
• Electricity is made from energy – transferred
through power lines – made back into energy
• Green
– Doesn’t harm environment
Today in class
• https://www.schooltube.com/video/c74a9a49
5e7544dba30a/bill%20nye%20-%20motion
(25 minutes)
Circuits Lab answers
Science Thought 9/20
Unit Test
Turn to Circuit Lab in INB
Log into google classroom
25 questions
Then physics scavenger hunt
How do kinetic and potential energy contribute
to the mechanical energy of an object?
• An object that possesses mechanical energy
is able to do work.
– Mechanical energy
• Kinetic
–Energy of motion
• Potential
–Energy of position
• Involved in the operation of simple
machines