Transcript Modified Chapter One, Unit F

Forces and Motion
Science Question of the Day
 What causes the noise when you crack your joints?
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Gravity
 Gravity is a specific kind of _____________.
 A force is simply the ________ or a _________ on an
object.
 Can you think of some examples of pushes and pulls
on objects? ___________________________________
_______________________________________________
 Take my soccer ball for example…
 How about my yo-yo…
Gravity
 Kicking the soccer ball I am applying a force quickly to
an object.
 Forces can also be added over ________________.
 What are some examples of forces applied over time?
 Think about my car…
 Or an elevator…
Gravity
 Some forces are ___________________ acting on us.
 Gravity is an example of a ____________ that is always
acting upon us no matter where we are!
Gravity:
Take notes about the video here.
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Gravity
 Each piece of ____________________ in the universe
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no matter how large or how small _______________ on
one another.
This force is called ___________________.
We see this most on Earth with how objects ________
___ _______ ________________ like my bouncy ball.
Our gravity keeps everything _____ the earth, even the
oceans!
If we didn’t have __________ or we had a weaker
__________________ force, our water and some of our
atmosphere might ___________ _____ into space!
Gravity
 Even though gravity is what keeps us ______ the Earth,
it is a pretty ___________ force.
 My bouncy ball and soccer ball _____________ have
gravitational force.
 Do you think if I put them on the ground they will roll
toward one another? ___________
 Let’s find out…
Gravity
 What do you know about that? They didn’t roll
together!
 Why not?______________________________________
________________________________________________
 It’s not because of their size. ________ has nothing to
do with gravitational force.
 It depends of the ____________ of the objects and the
__________________ between them.
 Think about the planets. Jupiter is huge, but it’s
gravitational pull is ______ stronger than say Uranus.
It’s all about the ________, baby!
Mass and Gravity
 The more an object ______________ (weight is
relative, but we’ll use it here since we are all Earthlings,
I think…) the _____________ gravitational pull it has.
 Remember, we said that some objects can be very
_____________, but ___________ a lot while some
objects can be very __________ and weigh a
____________ amount.
 Take a marble and a beach ball for example. Which has
more mass? ________________________________
________________________________________________
Distance and Gravity
 The _________________ you are to something the
_________ gravitational pull you will feel.
 We notice this when we think about the sun and the
Earth.
 The sun is about 330,000 times more ___________ than
the Earth, but we feel the Earth’s gravitational pull
_________because we are ______________ to it than the
sun.
 Did you know that if you are standing on a mountain
top you have ________ gravitational pull from the Earth
than you do if you are standing at _____ _________?
Can gravity be measured?
 Yes! Gravity can be measured in a unit called
_______________.
 Any ideas as to why it is called a newton? __________
________________________________________________
 When we step on the scale we are measuring the
__________ of ____________ on ourselves.
 We can express our weight in _______________ just as
we can in ________________ as newtons.
Time for a laugh…
 When NASA first started sending up astronauts, they
quickly discovered that _____________ _______ would
not work in zero gravity. To combat the problem,
NASA scientists spent a decade and $12 billion to
develop a pen that writes in zero gravity, upside down,
underwater, on almost any surface including glass and
at temperatures ranging from below freezing to 300 C.
The Russians used a pencil.
 Get it? The Russians… Wow, that was funny!
Time for a little practice…
 Read “Gravity” and complete questions 1-6 for
homework.
The teacher asked little Johnny,
“What is the definition of infinity?”
Little Johnny replied,
“Tonight’s homework assignment.”
Science Question of the Day
 Why does pepper make you sneeze?
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Speed and Velocity
 When you apply ____________ to an object, you are
putting the object into _________________.
 We can observe the motion in many ways:
 Did the object move quickly? __________ Slowly? ______
 How far did the object go? __________________________
 Which direction did it move? _______________________
There are many ways in which we can observe motion.
Two ways we are going to look at today are ___________
and _______________.
Speed
 Let’s think about a pitcher and a baseball.
 How fast is he or she really pitching and how can we
determine this? ________________________________
________________________________________________
 How far is the pitcher’s mound from home plate?
________________
 How long did it take for the baseball to go from the
pitcher’s glove to home plate? ____________________
 The relationship between the ________ and the
_______ is the ____________.
Speed
 To calculate the speed, you must ___________ the
____________ by the ____________.
 Let’s try that in the classroom.
 How far am I from my volunteer? ________________
 How many seconds did it take for the ball to reach my
volunteer? ______________________
 Let’s do some math! ____________________________
________________________________________________
 We just used a ratio in real life! Ms. White would be
so proud!
 It is a comparison of the distance ___________ to time
that __________________ during the motion.
Speed
 We could even take this further and figure out how far
my ball could travel in an hour.
________________________________________________
 How many feet are in a mile? _____________________
 What equation could we make in order to determine
how many miles per hour my ball traveled? ________
________________________________________________
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Speed
 Speed is difficult to calculate at a __________.
 For example, the wind could affect how
quickly my ball is moving or the track in which it moves.
 If I’m driving a car, I may speed up or slow down depending
on traffic patterns.
 This is why we determine the __________ speed of objects.
 Here’s an example: A trip from here to Disney World is 756
miles. This trip can be made in 12 hours and 49 minutes.
 What average speed must we go to get there in this amount of
time? _____________________________________________
_____________________________________________________
Speed:
Take notes about the video here.
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Velocity
 Another way to observe motion is ____________.
 Velocity is the ________ of an object going _____ a
particular ______________.
 Suppose two cars pass each other in opposite lanes of
an east/west highway. Both cars are traveling at 75
mph, so both have the same speed. But the cars are
going in different direction, so they have ___________
_______________.
 One car has a velocity of 75 mph heading east and the
other is 75 mph heading west.
Velocity
 Velocity is simply _________ with a _______________.
 Think about a race car on a circular track.
 The speed may stay ____________, but the velocity
changes when the car changes ___________________.
Momentum
 Could you tell the difference between a bowling ball
that was painted like a soccer ball and a real soccer ball
rolling down a bowling lane? ________________
 When they hit the pins you could! The bowling ball
would knock the pins over, but the soccer ball would
only move a couple of pins.
 This is because the bowling ball is ______________
and would have more ______________________.
Momentum
 ________________ is the measure of how hard it is to
________ _________ or _________ an object that is in
motion.
 Think about football players. Is it easier to stop the
quarterback or the lineman? ____________________
 Duh, the quarterback because he is smaller and lighter.
 You can determine the ________________ of an object
by _________________ the _________ ____________
the velocity.
Momentum
 Let’s figure out the momentum of the bowling ball.
 The ball weighs 8 lbs.
 It is traveling at 3 mph.
 What is it’s momentum?
 How about the soccer ball?
 It weighs 1 lb.
 It is also traveling at 3 mph.
 What is it’s momentum?
 Obviously, the bowling pin is the linebacker in this
example.
Conservation of Momentum
 When the bowling ball struck the pins it created a
collision.
 There is a law of science that states that an object’s
momentum ______________ a collision stays the
_________ as momentum _____________ the collision
if no other forces act on the object.
 We can see this by the bowling pins absorbing the
force of the bowling pin and scattering in the lane.
 This is called the ________ of the ________________ of
momentum.
Time for a little practice…
 Read “Speed and Velocity” and answer questions 1-6
for homework tonight.
Science Question of the Day
 What is static electricity and how does it work?
The Laws of Motion
 There are several laws that were
discovered by scientists thousands of
years ago that describe how objects move.
 We all know about Newton and gravity,
but some you may not have heard of are
Galileo, Aristotle, and Ptolemy.
 Over the next few days, we will discover
Three Laws of Motion.
First Law of Motion
 An object at _______ tends to ________ at rest, while
an object in _____________ tends to stay in _________
in a straight line until an ___________ force acts on it.
 What does this mean?
 Objects do not change their velocity unless some force
_________ on them.
 Example: A hockey puck sitting on the ice does not
move until something makes it move.
 The puck will continue to travel in the same direction
across the ice until a stick changes it or friction slows it
down.
Friction
 Friction is a force that ___________ motion whenever
_________ surfaces rub against each other.
 Friction is only present when other forces such as
____________ or _________ ___________ are present
and act to _______ an object against something else.
 Friction is what causes objects that are rolling to
________ once the energy that keeps them moving is
________ than the energy that was required to make
them move.
 Let’s roll this ball and see what happens.
Inertia
 Objects tend to ____________ a change in motion.
 For example, when you are in your car and you go around a
curve, your body tends to want to go in the opposite
direction. This is because of ______________.
 This is the property that makes it hard to __________ a
car when it is parked, or _________ to stop it once it is
moving.
 Sometimes the first law is called the ______ of ________,
but inertia is not a law; it is a ______________.
Balanced & Unbalanced Forces
 Before we can learn about the Second Law of Motion,
we must first learn about ____________ and
_________________ Forces.
 Which one of these pictures if balanced? Unbalanced?
Balanced Forces
 We have been learning about forces such as gravity,
inertia, friction, etc.
 Most of the time, object have _________ than one
force acting on them at a time.
 A ball rolling across the floor is experiencing all three
of the above stated forces.
 ________________ forces are forces that are acting
_______________ on an object, but are acting in
________________ directions.
Balanced Forces
 When the forces are balanced, either the object does
_______ move, or it moves at a constant ___________.
This is called the ________ _____________.
 Think about a skier. What forces of motion are acting
on him? _______________________________________
Balanced Forces
 The skier continues down the slopes because the forces
of gravity, inertia, and friction are all _____________.
 Once he reaches the bottom of the slopes, the force of
___________ will overtake the forces of gravity and
inertia, and the skier will eventually stop.
 This is when ____________________ Forces take over.
Unbalanced Forces
 Unbalanced forces cause a _________ in velocity
making the object speed up, slow down, or change
direction.
 In a game of tug of war, two teams are ___________ on
the rope. If they are both ___________ with equal
force, than the forces are _________________ and the
net force is ______________; the rope does not move.
 However, if a team pull harder, then the rope starts to
move in their direction.
 This is an unbalanced ___________.
Unbalanced Forces
 Think about the following scenarios. How are
unbalanced forces acting on the objects?
 Speeding up a car
 Slowing down a car
 Changing the direction of a car
Here’s a hint: friction!
Forces:
Take notes about the video here.
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Time for a little practice…
 Read “Balanced and Unbalanced Forces” and answer
questions 1-5 for homework due tomorrow.
Science Question of the Day
 How and why do cats purr?
Second Law of Motion
 This law explains how an _________________ force changes
the motion of objects.
The __________ of an object is equal to its
mass _______ acceleration
 When unbalanced forces act on objects it ___________ the
___________ of the object (its speed, direction, or both).
 The rate of this change is called ______________________.
 This law states:
 The ___________ the force, the greater is the _____________,
or change in __________________.
 The greater the ___________, the __________________ is the
acceleration or change in velocity.
Second Law of Motion
 So basically, the ________________applied, the
__________ it will go. The ______________applied, the
_________________ it will go.
 And, the _____________you have in an object, the
_____________________is needed for acceleration,
 Take a miniature car for example vs. a real one.
 I can push the miniature with one finger with very little
effort, and it shoots forward.
 If I tried to do that with my car I would probably break
my finger.
Second Law of Motion
 The _________________ in which force is applied is
the direction in which the object ________________.
 For example, if an object is already moving and we push
it from behind it will simply speed up.
 Let’s have a little race.
Second Law of Motion
 If the _________ is applied from the _______________
direction the object is moving, then it will __________
down the object.
 For example, if we were to play bumper office chairs
(and we won’t for safety sake), and I were to push my
chair into someone else’s chair then it would slow down
or stop their motion.
 We see this in front-end collision crash tests.
Third Law of Motion
For every __________ force, there is an
________ and __________ reaction force.
 This basically means that forces always come in pairs.
 For example, as I am pushing down on this floor with
my feet, the floor is pushing back.
 The forces are always ___________ and ____________.
 If the floor did not push back, I would fall right
through.
The Laws of Motion:
Take notes about the video here.
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Time for a little practice…
You and a partner will be rotating through several
mini-experiments and recording your results over the
next few days.
2. All the activities are designed to help you understand
the different laws of motion.
3. At the end of each rotation you will fill out your
research guide. This is your final product that will
be due next week.
4. Please make sure your put effort into your research
1.
guides as they are
worth 100 points!