Transcript Unit 3 Force, mass and motion 1-19

Warm up 11/13
1. Although more than one form of heat transfer is present, which
type of heat transfer is heating up soup?
2. The bulb of a thermometer is placed in your mouth. Why does
the level of the liquid rises in the thermometer?
3. Why does the end of a spoon sticking out of a cup of hot water
also gets hot?
Unit 3
Force, mass, and the motion of objects
b. Demonstrate the effect of balanced
and unbalanced forces on an object in
terms of gravity, inertia, and friction.
c. Demonstrate the effect of simple
machines (lever, inclined plane, pulley,
wedge, screw, and wheel and axle) on
work.
Your boss is concerned about damage
being done to customer’s floors and
refrigerators as they are being moved
into their final resting place in the
kitchen (your refrigerator does not
come with wheels on the bottom).
Problem
Your job is to develop a better way to move
refrigerators into place that eliminates the
damage done to floors and the refrigerator.
Warm up 11/16
• You have 5 minutes to discuss your homework where you went and looked
up about “what do we need to know?” for the PBL moving the refrigerator.
• Then your group will share.
Work Session
• Read pages 124-127 do Section Review page 127 all
questions
• Read pages 128-132 do Section Review page 133 all
questions
Solution
• You will present your innovation using any digital tool you wish.
You must include
• Free Body Diagrams ( before the innovation & after the innovation )
• Description of your innovation (with pictures)
• Explanation of how & why it works. Why is it better than shoving the
refrigerator across the floor?
Warm up 11/17
• What may happen when an object receives unbalanced
forces?
• Give an example of something with balanced forces
acting on it.
• How does the roughness of surfaces that are touching
affect the friction between the surfaces?
Forces
•
•
•
•
Push/pull
Affect motion (acceleration ) of object
Measured in units called Newtons (N)
Occur in pairs (ex: person exerts force down on chair: chair exerts force up
on person)
• Often unseen : gravity, magnetism
• Has size and direction ( 10N →)
Types of forces
•
•
•
•
•
Fnet= Net Force: total of forces acting on an object
Fg = gravitational force
Fa= applied force (push or pull)
Ff = frictional force
Fn = normal force (opposes Fg)
Free Body Diagram
• A book is at rest on a tabletop. Diagram the forces acting
on the book.
Warm up 11/18
• A plastic bag is falling. Diagram the forces
acting on the plastic bag as it is falling.
• How do you get a net force of zero?
Classwork check
• Take out yesterday handout as well as the book
work from the section review on page 133.
• Swap papers with someone at your table.
Warm up 11/19
• Take everything off of your desk.
• Do not write on the test.
• Material managers get an iRespond for
everyone at your table.
Spring Scale Mini lab
• First off you need to zero your scale by moving the upper metal tab to have
the scale read zero.
• Record all data into a chart that you have created
• At a constant rate moving your weight attached to the spring scale measure
the force it takes for you to move the weight.
• Again everything is done carefully and at a constant speed mve the weight up
your ramp. Measure the force.
• Lastly measure the force it takes to lift the weight straight up.
Begin PBL refrigerator lab
• Begin the lab by first reading the directions.
• By tomorrow everyone will have had to of
completed the first free body diagram of your
refrigerator.
Warm up 11/20
What does friction force oppose?
What force opposes gravity?
Work session
• Work on PBL.
Quiz
• Clear everything off your desk `
Warm up 11/30
Free Write
• What science that we have learned about did
you encounter over the break?
• Be sure to explain…
Newton’s First Law
(law of inertia)
An object at rest tends to stay at rest and an object in
motion tends to stay in motion unless acted upon by
an unbalanced force.
Newton’s First Law
(law of inertia)
• MASS is the measure of the amount of
matter in an object.
• It is measured in Kilograms
Newton’s First Law
(law of inertia)
• INERTIA is a property of an object that describes
how much it will resist change to the motion of the
object.
• More mass means more inertia.
Work Session
• Work on PBL be sure to only use the black lined spring scale when
performing your trails.
• When you are finished with the PBL grab a Free Body Diagram review hand
out.
Warm up
• Get out modifications, all notes from
Refrigerator PBL and PBL hand out.
Work Session
• With your group members finish part 2 of the PBL
packet. Put modifications on your Refrigerator (brick).
• Once you have finished with the modifications begin
testing at your results. Today you will need to use your
phone as a timer to figure out acceleration.
• ONLY USE THE BLACK LINED SPRING SCALES.
• Start acceleration hand out.
3, 2, 1
• 3– I learned statements…
• 2 – Ahas, insights…
• 1 – Question I have is…
Warm up 12/7
• If you do not have a cell phone then come
grab a laptop.
• Go to Kahoot.it
Work Session
• You have 25 minutes to complete in altercations to your
PBL presentation. Everyone is presenting no excuses.
• If your group has presented and/or finished then come
up to the front table and grab a handout titled
“Calculating Net Forces”
Warm up 12/8
• After watching the video what force is missing that allows the two object to
hit the ground at the same time?
• https://youtu.be/KDp1tiUsZw8
• https://youtu.be/7eTw35ZD1Ig
• There are four main types of friction:
• Sliding friction: ice skating
• Rolling friction: bowling
• Fluid friction (air or liquid): air or water resistance
• Static friction: initial friction when moving an object
Newton’s Second Law
Force equals
mass times
acceleration.
F = ma
Newton’s Second Law
• Force = Mass x Acceleration
• Force is measured in Newtons
ACCELERATION of GRAVITY(Earth) = 9.8 m/s2
• Weight (force) = mass x gravity (Earth)
Newton’s Second Law
• Moon’s gravity is 1/6 of the Earth’s
• Weight (force) = mass x gravity (Earth)
• If you weigh 420 Newtons on earth, what will you weigh on the Moon?
• If your mass is 41.5Kg on Earth what is your mass on the Moon?
Newton’s Second Law
• WEIGHT is a measure of the force of
gravity on the mass of an object
________
Newtons
• measured in __________
Warm up 12/10
• How do you get a net force of zero?
• What force opposes gravity?
Newton’s Third Law
For every action there is an equal and opposite
reaction.
Think about it . . .
What happens if you are standing on a
skateboard or a slippery floor and push against
a wall? You slide in the opposite direction
(away from the wall), because you pushed on
the wall but the wall pushed back on you with
equal and opposite force.
Why does it hurt so much when you stub
your toe? When your toe exerts a force on a
rock, the rock exerts an equal force back on
your toe. The harder you hit your toe against
it, the more force the rock exerts back on your
toe (and the more your toe hurts).
Reaction: road pushes on tire
Action: tire pushes on road
Newton’s 3rd Law
• Suppose you are taking a space walk near the
space shuttle, and your safety line breaks.
How would you get back to the shuttle?
Newton’s 3rd Law
• The thing to do would be to take one of the tools from your tool
belt and throw it is hard as you can directly away from the shuttle.
Then, with the help of Newton's second and third laws, you will
accelerate back towards the shuttle. As you throw the tool, you
push against it, causing it to accelerate. At the same time, by
Newton's third law, the tool is pushing back against you in the
opposite direction, which causes you to accelerate back towards
the shuttle, as desired.
Review
Newton’s First Law: Objects in motion tend to stay in motion
and objects at rest tend to stay at rest
unless acted upon by an unbalanced force.
Newton’s Second Law:
Force equals mass times acceleration
(F = ma).
Newton’s Third Law:
For every action there is an equal and
opposite reaction.
Vocabulary
• Friction
• Force
• Gravity
• Inertia
• Speed
• Net force
• Acceleration
• Velocity
Human Paragraph
• Everyone in your group will make a sentence.
The first person starts and the rest of the
group follows with their own sentence that
goes with what you have learned today.
Take everything off your desk
Motion; Speed;
Velocity;
Acceleration
What Is Motion?
• Motion is when an object changes place or position. To properly
describe motion, you need to use the following:
•
•
•
•
Start and end position?
Movement relative to what?
How far did it go?
In what direction did it go?
What Is Speed?
•Speed is the distance an object travels in a
certain amount of time.
•To calculate speed, you use the following
formula:
Speed (s) = Distance (d)
Time (t)
Speed Math Problem
•Suppose you ran 2 km in 10 min.
What is your speed?
S = 2 km = 0.2 km/min
10 min
Another Problem
•What is the speed of a car traveling 144 km in 90 minutes?
_______________ km/h
•In miles per hour? __________ mph
Velocity
•Velocity is the speed of an object, but the direction is also
included. It is calculated the same as speed, but you must
include a direction in your answer.
•Example: the bass boat was moving 12 mph toward the
north.
Velocity Problem
• Indicate which of the following are
velocities:
a.
b.
c.
d.
125 cm/sec
30 km/h northwest
350m/sec north
520 km/h
Acceleration
•Acceleration is the rate of
change of velocity. A change
in velocity can be either a
change in speed, or direction,
or both.
•Deceleration is when
acceleration has a negative
value.
Acceleration
• The formula for calculating acceleration is:
• Acceleration (a) = final velocity (vf) – initial velocity (vi)
time (sec)
• The unit for velocity, in this case, is
m/s/s
OR
m/s2
Acceleration Math Problem
• A jet starts at rest at the end of a runway and reaches a
speed of 80 m/s in 20 s. What is its acceleration?
• Acceleration (a) = final velocity (vf) – initial velocity (vi)
•
time (sec)
• a = 80 m/s – 0 m/s = 4 m/s2
• 20 sec
Acceleration Math Problem
• A skateboarder is moving in a straight line at a speed of 3 m/s
and comes to a stop in 2 sec. What is his acceleration?
a = 0 m/s - 3 m/s = -1.5 m/s2
2 m/s
Boggle
• 2 minutes: Study notes
• 2 minutes: Record any information you can remember without notes
• 2 minutes: Share with one other student. Add his/her knowledge to your
list.
• 2 minutes: Leave your buddy. Compare with another student. Receive a point
for each fact that you have that the other student doesn’t have.
Warm up 12/14
• Which planet has more gravity Earth or Jupiter? Why?
• What is the acceleration of a car the was traveling at 40 km/s and had to
slam on it’s brakes and stop to avoid a wreck in 2 seconds?
Catapult Lab
• Grab the materials needed.
• 2 Big popsicle sticks
• 8 small popsicle sticks.
• 4 rubber bands
• 2 small plastic cups.
• Grab a catapult lab packet.
Clean up your area.
Warm up 12/15
• What is the speed of a car that goes 10 miles in 10 minutes?
• What is force?
Warm up 12/16
• Calculate the following acceleration problem: A roller coaster's original
velocity is 0 km/s and its final velocity is 30 km/s. The roller coaster ride
takes 60 seconds to complete. Find the acceleration.
Warm up 12/17
• What is your weight on a planet that has 10N of acceleration if your mass is
15kg?
Work Session
• Bill Nye Video
• Read pgs. 150-156
• Complete the section review on page 157.
Closing
• Go over Questions from Section Review.
Warm up 1/5
• Happy New Years!
• Come in get your science notebook and have a seat.
• Write down at least five sentences about things you did over the break that
relate to the science we have learned about so far.
Rules and Procedures
• What are in class rules?
• What are our procedures?
D.R.A.W.
• Yes, it is back and every Tuesday we will have D.R.A.W. lessons.
D.R.A.W.
• Explain the physics of force, mass and acceleration for a NASCAR race car
coming out of the pits.
• Draw a free-body diagram for a race car rounding a curve during a race.
• A small, fairly light drag race car accelerates from the starting line at a high
rate of speed. Later, a different car, having 3 times as much mass but with
an engine that delivers 4 times the force, takes its turn. What is the
acceleration of the second car compared to the first car?
Warm up 1/6
•What is the difference between
mass and weight?
Quiz
Take everything off of your desk except
something to write with.
Material Managers grab folders and quiz for group
memebers.
Work Session
• You have the opportunity to pick 3 boxes in which you want to complete for
this choice board. This will be due tomorrow by the end of class. This will
counted as 2 classwork grades.
You’re stuck here until…
Your group is responsible for defining one of the
vocabulary words of this unit in your own words.
•
•
•
•
Group 1- Friction
Group 2- Force
Group 3- Gravity
Group 4- Inertia
•
•
•
•
Group 5- Acceleration
Group 6- Velocity
Group 7- Motion
Group 8- Net Force
Warm up 1/7
• What is the difference between
velocity and speed?
• What is the relationship between
acceleration and velocity?
Work Session
• Continue working on your choice board they are due 10 minutes before the
end of class.
• When you finish the 3 you have chosen you may continue and do more
selections for extra credit.
• Turn in to the cubby for your class.
Closing
Be the teacher…
• I will start by throwing the football to a student in
which they must answer the question I ask.
• The next step the student will throw the football to
another student and ask them a question on what
we have been going over in this unit.
Warm up 1/8
•What is inertia?
•What law talks
about inertia?
Warm up 1/8
• What is inertia?
• a tendency to do nothing or to remain unchanged
• What law has talks about inertia?
• Newton’s 1st law.
4 Fold Vocabulary Game
• Begin by folding papers into rows, each row having four sections. Fold paper
in half until you have 16 boxes.
1st box- WORD
2nd- PICTURE
• Friction
• Force
• Gravity
• Inertia
3rd-DEFINITION
• Acceleration
• Velocity
• Motion
• Net Force
4th- SENTENCE
Kahoot.it
• Take out your phones
• If you do not have one with you today than come
grab a laptop.
Warm up 1/11
Which picture would have more gravitational force?
Why?
•A
•B
Work Session
• Take out 3 sheets of paper.
• You will create a 6 page flip book on Inertia and Newton’s 1st Law.
• Follow all directions on the handout.
I Care Why…
• Inside outside circle. 3 rotations. Stop when the music stops and
talk with the person in front of you.
• Explain the relevancy of Inertia and Newton’s 1st law to your life.
• How might you use knowledge about inertia in your life?
• The people in the hot seat will share what someone else shared
with them.
Warm up 1/12
• If a person holds a book, what forces are acting on the
book? Is there a net force present?
• You toss a ball into the air. Before you release the ball
(while your hand is moving) what forces are acting on
the ball on its way up? On its way down?
D.R.A.W
• The First Law of Motion in a Car Crash
• Annotate the article.
• Write one way you can connect to this article to your life and make
one connection to the world.
• When finished turn into the appropriate tray. Then you can play the
4 fold game with someone else who is done but this is to be done
silently.
Kahoot
• If you have a phone go to Kahoot.it and wait for my pin.
• If you do not have a phone to play grab a laptop at the front. Be careful as
there is 2 cords plug in to the laptops.
• When turning them in just log off and plug both cords back into it.
Quiz
• Clear everything off of your desk.
• Material Managers come up grab a
folder and a quiz for everyone in your
group.
Simple Machine PBL lab
• Lab safety and behavior expectations.
• DO NOT get a big ramp without my permission.
• Calculations and spring scale use.
• Material managers- Brick with your group number,
Spring scale, dry erase board, ruler, and 2x4.
Snowstorm
Write down what you learned on a piece of
scratch paper and wad it up. On my count you
will throw the paper snowballs in the air. Then
each of you pick up a nearby response and
reads it aloud when I ask you to share.
Warm up 1/14
• What is the difference between static and
sliding friction?
Work Session
• Continue to work in the Lab we do not have anymore days to finish so
everything must be completed today.
• If you finish you may start your homework.
• If you finish the homework take out your 4-fold game and work with a
partner at your table.
So what????
• What in 10 years from now will be important to take
away from this lesson?
• In your group discuss for 5 minutes what is important
about this lesson. Your communicator will give your
groups answer. Write down if needed.
Warm up 1/15
• What is the formula for work?
• If Griffin construction company needs to build a ramp that will
need to go up a height of 10 meters and they would like for the
people using the ramp to only have to exert a force of 2N what
would have to be the distance of the ramp?
The 6 Simple Machines
Inclined Plane
Screw
Pulley
Lever
Wedge
Wheel and Axle
Definitions:
Energy: Ability to do work
Work= Force x Distance
Force: A Push or a Pull
Inclined Plane
Inclined Plane
• The Egyptians used simple machines to build the pyramids.
One method was to build a very long incline out of dirt that
rose upward to the top of the pyramid very gently. The
blocks of stone were placed on large logs (another type of
simple machine - the wheel and axle) and pushed slowly up
the long, gentle inclined plane to the top of the pyramid.
Inclined Planes
• An inclined plane is a flat surface
that is higher on one end
• Inclined planes make the work
of moving things easier
Work input and output
• Work input is the amount of work done on a machine.
• Input force x input distance
• Work output is the amount of work done by a machine.
• Output force x output distance
Inclined Plane Mechanical Advantage
• The mechanical
advantage of an
inclined plane is equal
to the length of the
slope divided by the
height of the inclined
plane.
• While the inclined plane
produces a mechanical
advantage, it does so
by increasing the
distance through which
the force must move.
Screw
The mechanical advantage of an screw can be calculated by
dividing the circumference by the pitch of the screw.
Pitch equals 1/ number of turns per inch.
Wedges
• Two inclined planes
joined back to back.
• Wedges are used to split
things.
Wedge – Mechanical Advantage
• The mechanical advantage of a wedge can be found by dividing the length of
either slope (S) by the thickness (T) of the big end.
S
T
• As an example, assume that the length of the slope is 10 inches and the thickness
is 4 inches. The mechanical advantage is equal to 10/4 or 2 1/2. As with the
inclined plane, the mechanical advantage gained by using a wedge requires a
corresponding increase in distance.
First Class Lever
Fulcrum is between EF (effort) and RF (load)
Effort moves farther than Resistance.
Multiplies EF and changes its direction
The mechanical advantage of a lever is the ratio of the length of the lever
on the applied force side of the fulcrum to the length of the lever on the
resistance force side of the fulcrum.
First Class Lever
.
• Common
examples of
first-class
levers include
crowbars,
scissors, pliers,
tin snips and
seesaws.
Second Class Lever
RF (load) is between fulcrum and EF
Effort moves farther than Resistance.
Multiplies EF, but does not change its direction
The mechanical advantage of a lever is the ratio of the distance from the
applied force to the fulcrum to the distance from the resistance force to the
fulcrum.
Second Class Lever
• Examples of
second-class levers
include nut crackers,
wheel barrows,
doors, and bottle
openers.
Third Class Lever
EF is between fulcrum and RF (load)
Does not multiply force
Resistance moves farther than Effort.
Multiplies the distance the effort force travels
The mechanical advantage of a lever is the ratio of the distance
from the applied force to the fulcrum to the distance of the
resistance force to the fulcrum
Third Class Lever
• Examples of thirdclass levers include
tweezers, arm
hammers, and
shovels.
Pulleys
• Pulley are wheels and
axles with a groove
around the outside
• A pulley needs a rope,
chain or belt around the
groove to make it do
work
Diagrams of Pulleys
Fixed pulley:
Movable Pulley:
A fixed pulley changes the direction of a
force; however, it does not create a
mechanical advantage.
The mechanical advantage of a
moveable pulley is equal to the number
of ropes that support the moveable
pulley.
COMBINED PULLEY
• The effort needed to lift the load is
less than half the weight of the
load.
• The main disadvantage is it
travels a very long distance.
WHEEL AND AXEL
• The axle is stuck rigidly
to a large wheel. Fan
blades are attached to the
wheel. When the axel
turns, the fan blades spin.
Wheel and Axel
• The mechanical advantage of a wheel and axle is the ratio of the radius of the wheel
to the radius of the axle.
1
5
• In the wheel and axle illustrated above, the radius of the wheel is five times larger
than the radius of the axle. Therefore, the mechanical advantage is 5:1 or 5.
• The wheel and axle can also increase speed by applying the input force to the axle
rather than a wheel. This increase is computed like mechanical advantage. This
combination would increase the speed 5 times.
GEARS-Wheel and Axel
• Each gear in a series
reverses the direction of
rotation of the previous
gear. The smaller gear
will always turn faster
than the larger gear.
Boggle
• 2 minutes: Study notes
• 2 minutes: Record any information you can remember without notes
• 2 minutes: Share with one other student. Add his/her knowledge to your
list.
• 2 minutes: Leave your buddy. Compare with another student. Receive a point
for each fact that you have that the other student doesn’t have.
Warm up 1/19
• A shovel is an example of what simple machine?
• A zipper is an example of what simple machine?
Work Session
• You will begin to make a pamphlet/brochure on the
advantages and disadvantages of using simple machines.
• This will need to printed and turned in at the end of class
tomorrow no exceptions.
Dramatize it…
• At least one group member or as many as you want must
act out as if they where using a simple machine. In your
group plan out how this person will act it out.