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Unit 6 PS
Standard PS 5
Drill Panther
Copy down the Speeds of Animals
MAKE A BAR GRAPH WITH THESE ANIMALS AND
THEIR SPEEDS ON IT
Animal Name on X axis
Pig 11 mph
Mouse
8 mph
Six-lined race runner 18 mph
Elephant 25 mph
Moose
35 mph
Lion 50 mph
BAR GRAPH
Panther Drill
Copy this equation: This how to figure out your
speed in miles per hour
75 ft X
1 mile
X
3600 sec
your
5280 ft
1 hr
Your SPEED
Speed = Distance divided by time
For us today:
ft/sec
Unit 6 Motion
Motion: movement of an object from a fixed
point.
Fixed point is called the reference point (this is
the starting line)
Distance
Distance how far something has moved. IE How far
you drive in your car. It is only a number or
amount.
For instance LCHS is exactly 61.3 miles from my door
to the parking lot. This is distance.
Displacement
Displacement: is a distance and a direction. For
example to get to the deer stand in the woods I had
to walk 1500 yards North west from the road.
Total or Final Displacement: change in position from
the starting point.
LOOK AT EXAMPLE ON THE NEXT SLIDE
Total displacement
You travel:
6 miles east
then
3 miles west
6 miles E
3 miles W
Total displacement (distance from where you started) =
6 miles – 3 miles = 3 miles. You am now 3 miles from your
house.
Panther Drill
What is the difference between speed and velocity?
Speed
Speed: the distance traveled per unit of time.
s=d/t
Different speeds
Speed (s) = distance (d)/time (t)
meters/sec
Cruise control on a empty road= constant speed
Bumper to bumper traffic = changing speed, your
speed is fast, then slower, then faster, then slower
ect
Speed and Velocity
Speed: we already know is the distance
traveled in a given unit of time. Measured for
science in meters per second. Can also be
mph
Velocity: speed with direction 22 m/sec SE IE:
You have to walk 2.8 mph NW from the road
into the woods to the deer stand.
You are
here
Speed =
22 mph
Velocity =
22 mph
North East
Speed =
22 mph
Velocity =
22 mph
NorthWest
Who cares? You should. The red case means your butt could
be toast!!! Hurricane coming right at us!!!!!!
The purple case velocity means surfs up dude!!!
Hurricane Fran 1996
Different speeds
Constant Speed: when speed is unchanged. like
cruise control in the car.
Changing speed: speed is not constant or consistent.
Like stop and go traffic.
Average Speed: used when speed is changing, =
s (avg) = Total Distance Traveled
Total time spent traveling
Different speeds 2
Instantaneous Speed: Speed at any given time, only
true at that instant it is observed.
Instantaneous Speed
Ferrari Enzo 0-60 time 3.3
secs. The speed at any
time over that 3.3
seconds would be
different.
Exit
Explain the difference between speed and
velocity.
Panther Drill
If the formula for speed is s=d/t, write down
how to find distance and how to find time,
using the same equations.
t = d/s
d = s xd
Vid Clip
VIDEO
Acceleration: (a) the rate of change in velocity per
unit of time
Acceleration =
Velocity(final) - Velocity(original)
time
Original or Initial Velocity= 20 m/sec
Final velocity = 80 m/sec
Time = 2 sec
a=
a=
80m/s – 20m/s
2 sec
60m/s / 2 sec
30 m/sec
A car traveling at 60 mph accelerates to
90 mph in 3 seconds. What is the
car’s acceleration?
Acceleration
=
Velocity(final) - Velocity(original)
time
=
=
90 mph - 60 mph
3 seconds
30 mph
3 seconds
= 10 mph/second
Acceleration Units
The Unit for Acceleration in science is meters
per second per second or m/s2
a
= V final – V Initial
time
m/s
s
Panther Drill
If you are traveling at 4 m/sec and then speed
up to 12 m/s in a period of 5 seconds. What is
your acceleration
Tuesday 2/15
Panther Drill
18
Velocity
in m/s
16
14
12
10
8
6
4
2
0
1
2
3
4
5
6
7
8
Seconds
Use the graph to find out what is the acceleration between 3
seconds and 7 seconds
Extra Credit: What is the slope of the line?
PD Answer
Acceleration (a) = Vf – Vi
Vf = 14 m/s
t
time = 7 sec – 3 sec = 4sec
Vi = 6 m/s
14 – 6 = 8/4 = 2
4
2
m/s
Extra Credit
Slope:
3–7
6-14
m= (y1-y2)
(X1-X2)
=
-4/-8
m=2
??QUESTION??
Is the acceleration changing when you look at
the graph? Yes
At what kind of rate, changing or constant?
Constant
What do you see when you compare the slope
with the acceleration?
They are =
Slope of the line = the acceleration!!!!
Example
Joval and Justice pull up to each other at a stop
light. They decide to race. The 2 cars
accelerate as a traffic light turns green. In 5
seconds, Joval (car 1) goes 0-40km/hr and
Justice (car 2) goes 0-50 km/hr. Which car
accelerates the fastest?
Car 1:
Given:
Useful Equations
Unknown
Substitute
Evaluate Answer
Joval’s Car:
Given:
WHAT IS GIVEN
IN THE PROBLEM
Unknown
WHAT DO YOU NEED
TO FIND OUT?
Evaluate Answer DOES THIS MAKE SENSE?
Useful Equations
a
Substitute
v f  vi
t
Car 1:
Given:
Useful Equations
Time: 5 sec
Vi: 0
Vf: 40
Unknown
ACCELERATION
a
Substitute
v f  vi
t
HERE YOU WOULD do
calculations
Evaluate Answer DOES THIS MAKE SENSE?
Car 1:
Given:
Useful Equations
Time: 5 sec
Vi: 0
Vf: 40
a
Unknown
Substitute
acceleration
a= (40
Evaluate Answer DOES THIS MAKE SENSE?
YES
v f  vi
t
km/hr-0 km/hr)
5 sec
a = 40/5 = 8 km/hr/s
Car 1:
Given:
Useful Equations
Time: 5 sec
Vi: 0
Vf: 40
a
Unknown
Substitute
acceleration
a= (40
v f  vi
t
km/hr-0 km/hr)
5 sec
a = 40/5 = 8km/hr/s
Evaluate Answer DOES THIS MAKE SENSE?
YES
You do car #2
What is its acceleration?
Panther Drill
Define the following:
1. Constant acceleration
2. Changing acceleration
3. Positive acceleration
4. Negative Acceleration
Positive and Negative Acceleration
Positive acceleration: speeding up
Velocity
Acceleration
Negative acceleration: slowing down
Velocity
Acceleration
Velocity is still in the same direction
G
r
a
p
h
i
n
g
Positive
acceleration
Negative
acceleration
The area in red is where constant velocity
occurs.
Here there is 0 acceleration
Velocity m/s
25
20
15
Velocity m/s
10
5
0
1
2
3
4
5
6
7
8
9
10
Seconds
11
Changing Acceleration
In changing acceleration
the graph is not a
straight line with a
constant slope.
Changing acceleration is
speeding up or slowing
down.
Work
Lets check it: Vi = 22 Vf = 22 t = 7 (10-3 sec)
22-22 = 0/7 = 0m/s2
7
Velocity m/s
25
20
15
Velocity m/s
10
5
0
1
2
3
4
5
6
7
8
9
10
11
Seconds
Graphing
Draw a sketch of positive, negative, constant,
and zero acceleration on graph paper. Label
each sketch. Make sure you title the sketches
and tell me what each axis measures.. Divide
the graph paper in into quarters. Put each
graph in a separate ¼ of the paper.
Exit Assignment
Velocity Vs Time
30
25
20
15
Velocity Vs Time
10
5
0
1
2
3
4
5
6
7
8
9
10
11
12
13
Circle the area where there is positive, negative, and 0 acceleration.
Monday
Students will construct time-distance graphs
PS 5.6 Represent the linear motion of objects on
distance-time graphs.
Panther Drill
In your own words describe
Distance
Displacement
Speed
Velocity
0 speed and 0 Acceleration
Constant Speed and Acceleraton
Positive (Changing) Acceleration
Negative Changing Acceleration
PRACTICE
On your graph paper graph the following
data
Compare the speed of the 2 objects on a graph
Looks like this
Panther Drill
#1
D14
I 12
10
s
8
t6
a4
n2
c0
e
Describe what type
of motion or motions
that each graph
shows
#2
16
1
2
3
Time
4
5
6
V 14
E 12
L 10
O8
C 6
I 4
T 2
Y 0
1
2
3
4
Time
5
6
7
ANSWERS
#1) Increasing speed, Constant Rate Speed,
would be acceleration if y axis = velocity
and not distance
#2) Slowing down, negative and changing
acceleration
Story Graph
A student walks 25 ft west in 3 secs
Then the student stops and talks to his friends
for 5 secs.
The student then walks 30 feet west in 6 secs
Then the student realizes he will be late for class
and then walks a lot faster he travels 100 feet
in 5 secs
Tues
Panther Drill
How does the force applied to an object affect
its acceleration?
Lab pp 58 Text
Wednesday
Start Car LAb
Panther Drill
14
D
I
s
t
a
n
c
e
12
10
8
6
4
2
0
1
2
3
4
5
6
7
8
9
10
11
12
Time
1. Write down a few sentences to describe
what is happening in the graph. Similar to
the graphing exercise yesterday.
13
Preview
What is a Force:
Push or pull on an object.
Examples?
Passing a Basketball or Kicking a soccer ball
Returning Serve in tennis match
Stepping on the brakes
Catching Line drive.
What affect to you think force applied to an
object has on acceleration?
What affect to you think force applied to an object
has on acceleration of the object?
When force is increased in the same direction as the
acceleration, then the acceleration increases.
When force is applied or increased in the opposite
direction acceleration will lessen.
When force is applied in another direction besides
opposite, acceleration can change because the
direction will change and acceleration is a measure
of velocity and velocity includes direction.
Lab On THURSDAY
Get a book and open to pp 58-59
Pre-Lab
1) Write a hypothesis of what you think will
happen in the lab.
2) List the 2 forces you will apply to the car to
change acceleration and how you apply
those forces.
3) On a separate sheet of paper create a data
table that looks like this.
Monday
Panther Drill
List 3 things you do to change a objects motion
or acceleration
Force and Motion
As we know force is a push or a pull
We also know that forces cause movement.
Can an object have more than 1 force acting on
it at 1 time? YES
What are some examples?
Net Force: the total of all forces action on an object
Force is represented in a diagram by an arrow. The
arrow shows the direction the force is pushing or
pulling
Net Force
** Remember the force has a number (or
magnitude) and a direction**
When you have balanced forces, net force = 0.
How do you measure force?
Force is measured in NEWTONS
Newton: force necessary to provide a mass of
one kilogram with an acceleration of one
meter per second per second.
NEWTON = (n)
Forces
Does applying a force to an object always change
velocity?
Like we just saw an object can have more than 1 force
acting on it and not have the motion or velocity
change.
Balanced forces: forces of equal size (amount or
magnitude) acting on an object in opposite
direction that cancel each other out.
10n
10n
What force acts on us all the time?
GRAVITY
Gravity is always holding us down on the earth, and
the = force of the ground is pushing us back so we
stay planted on the ground.
What is this an example of?
BALANCED FORCES
Gravity pulls an object down, but the object is
pushed up by the ground or floor it stands on, so
the object does not move this is balanced forces.
Unbalanced forces: when 2 or more forces are
action on an object that are unequal. The
object will move in the direction that the
stronger force is pushing it.
volunteers
Net Force
** Remember the force has a number (or
magnitude) and a direction**
When you have balanced forces, net force = 0.
When you have unbalanced forces net force = a
number other than 0, the number can be + or –
and has a direction
Force Diagrams
Force Diagram: the rectangle
represents the object being
studied. The areas represent
the forces acting on that
object.
If you are jumping in
the air, your legs
produce a force to
overcome gravity the
force diagram would
look like this:
900 N
F net= 412 N
588 N
Demo
Force Diagram
Since the object
stopped going
downward, the
force applied to the
object by the spring
becomes = to the
force of gravity
Inertia
Inertia: the tendency of an object to resist change in
its motion.
To get an object to change its motion or velocity a
force needs to be applied to greater than the force
that is already acting on it.
The larger the amount force that is needed to change
the motion or velocity of an object the greater the
inertia of the object.
Which on of these will require the strongest force to
change its motion?
Bowling ball
Which on has the greatest inertia?
Bowling ball
Which of these has the greatest mass? Bowling ball
The more mass an object has, the
greater its inertia.
NEWTONS LAWS
Newton’s 1st law of motion states: An object at rest
stays at rest and an object in motion stays in
motion with the same speed and in the same
direction unless acted upon by an unbalanced
force. ALSO KNOWN AS LAW OF INERTIA
Any body shoot pool?
Newton’s Law in Action
What forces are in the
break in a game of
pool?
Cue stick-cue ball
Cue ball-Other balls
Balls hitting each
other
Are these forces
balanced or
unbalanced
Unbalanced
How does this show the law
of inertia?
The balls are resting until a
greater force of the cue ball
makes them move.
Tuesday
Panther Drill
Finish Inertia (5)
Pre-Video Quiz (5)
Video w/ quiz (25)
Post Video Sheet (10 min)
Newtons 2nd law
Panther Drill
Describe the law of inertia.
Wed
Panther Drill
Friction Notes
Friction Demo
Start Newton’s second law notes
Exit ticket
Panther Drill
1
Which of the
following is a
force?
A. Acceleration
B. Inertia
C. Friction
D. Velocity
2 Which of the following best
describes an objects
constant velocity
A. Its direction is changing
B. Acceleration is positive
C. Acceleration is negative
D. Acceleration is zero
What force that is holding the block in place on the
incline?
FRICTION
Friction: the force that opposes the motion or
attempted motion of one surface across another
surface.
To over come the force of friction and make the
block move a stronger force must be applied to the
block to create unbalanced forces.
Friction What causes it?
The sticking together of microscopic bumps on an
object. The “sticking together” are called microwelds.
The larger the mass of the object the stronger the
micro-welds, the more friction there is.
Friction depends on mass not contact or surface area
Friction
Where is the friction greater object A or B? WHY?
RAISE YOUR HAND DON’T CALL
OUT
A
B
2 kg
3
kg
Lab table
3 KINDS OF FRICTION
Static friction: “The frictional force that prevents to
surfaces from sliding over or past each other”
Stationary or still objects, basically what holds an
object from sliding across surface when you push
on it. The force you applied was not great enough
to overcome the micro-welds.
Caused by the force pushing down and up on the
object.
Micro-welds
Explains why more force was required to move
the blocks once we added the bars in our demo.
3 KINDS OF FRICTION
Sliding Friction: is the force that opposes the motion
of 2 surfaces past each other after static friction
has been broken. Only on objects moving already.
The force of sliding friction is in the opposite
direction of the applied force.
Applied Force
(push)
More
mass =
More
Friction
Sliding
friction
Sliding Friction
Push the book across the floor
Sliding friction occurs as the book’s surface moves
across the floor. Sliding friction is the opposite
force as your “PUSH”.
Will the book keep going if you stop pushing?
NO, as the force pushing is stopped, sliding friction
slows then stops an object.
Then static friction takes over.
3 KINDS OF FRICTION
Rolling Friction: The friction between a rolling
object and the surface it rolls on.
The friction between the rolling tires and the ground
is called rolling friction.
•
• Rolling friction is much less friction than static or
sliding friction. That is why it is easier to use a
dolly than pushing your kid brother in the box.
Start PD 4
Air Resistance
• Acts on objects on objects that fall through
the air
• The force of air resistance is in the opposite
direction to the force of gravity
• Air resistance affects anything that moves in
earth’s atmosphere
• Air resistance is pushing up as an object falls
due to gravity
• Depends on speed, size and shape of object.
Air resistance
START PD 7
Terminal Velocity
• When the forces on the falling object are
balanced and the object no longer accelerates
• When it falls with a constant speed called the
terminal velocity
Thursday
Panther Drill
Sound Travels at a speed of 330 m/s. How long
does it take for the sound of thunder to travel
1485 meters?
s = d/t
t = d/s
A) 45 seconds
s=
330
m/s
B) 4.5 seconds
d = 1485 m
C) 4900 seconds
D) 0.22 seconds
t= 1485m/330m/s
t= 4.5 seconds
SHOW WORK!!!!!!
Newton’s
nd
2
Law of motion
Force and Acceleration
The other day we talked about Newton’s first law of
motion that basically says that an objects motion
can only change if an unbalanced force acts on it.
How is a 60 mph fastball different than a 95 mph
fastball?
DUH the speed right? And the force it is thrown
with.
Also the acceleration of the faster pitch is
greater because its velocity changes more over
the same distance
EVIDENCE
a of 60 mph fastball:
Vfin = 60 mph Vin = 0 mph
60 – 0 / 60.5 = .99 m/h2
Distance = 60.5 feet.
a of 95 mph fastball
Vfin = 90 mph Vin = 0 mph Distance = 60.5 feet.
90 – 0 / 60.5 = 1.49 m/h2
Newton’s 2nd Law of motion
Mass and Acceleration
If you throw a baseball and shot-put as hard as you
can (with the same force) will the move at the same
speed?
NO!!!
WHY?
The shot is much heavier (greater mass) and it
requires much more force to make it move at the
same speed as the baseball
Baseball = .14 kg
High School Shot = 4 kg
NEWTON’S SECOND LAW OF MOTION
NEWTON’S SECOND LAW OF MOTION: the
acceleration of an object is in the same direction
as the net force acting on the object, and the
acceleration can be figured out using the following
formula:
acceleration (in m/s2) = net force (in newtons)
mass (in Kg)
a=
F net
m
NEWTON’S SECOND LAW OF MOTION
You can use the formula to find net
force or mass if you know the 2
other variables.
F net = m x a
F net = net force
m = F net
a
a = acceleration
m = mass
Force Calculated
A rocket engine provides 28,913 Newtons of thrust.
The rocket has a mass of 2,350 kilograms. Calculate
its acceleration if it moves HORIZONTALLY (we don’t
want to fight gravity yet).
a=
F net
m
=
28913 N
2350 kg
=
12.30 m/s2
YOU TRY
1) Find the mass:
You push on a skateboard with a force of 10 N and
it accelerates at 1.5 m/s2
What do you have given in the problem?
a = 1.5 m/s2 & force 10 N
What do you need to find? MASS
6.67 Kg
M = Fnet / a ; 10 N/ 1.5 m/s2 =
Panther Drill
What is Newtons 2nd law?
If your net force is 25 newtons and your
acceleration is .5 m/s2. What is the mass in kg
of the object?
More
A truck accelerates at 10 m/s2 with a force of
1500 newtons. What is the mass of the truck?
Have: a & Fnet
Need: mass
Formula: m = Fnet/a
Solve: m = 1500/10
ANSWER: 150 Kg
Friday
Problems Newtons 2nd law
Tuesday
• Gravity
Panther Drill 3/8
Define gravity in your own
words.
Gravity
Gravity: an attractive force between any 2 objects,
that depends on the mass of the objects and the
distance between them.
If the mass of one of
the objects increases
then the of attraction
between the 2 objects
increases.
Gravity
As the distance between 2 objects decreases then
the gravitational force between them increases.
As the distance between 2 objects increases then the
gravitational force between them decreases.
Gravity
Newtons Universal Law of Gravity:
(F) gravitational force = G x (m1 x m2)
d2
G is a constant
m = mass
d = distance between the 2 objects.
The force of Gravity
Lets figure out the force of attraction (gravity
between the earth and the moon
Distance between the 2: 384,403 km
Mass of moon: 7.36 × 1022 kilograms
Mass of earth: 5.9742 × 1024 kilograms
Set up the equation and we will do the math
together.
Get w/ your partner
Each partner will do one of the questions and
then explain their answer to their partner.
A/B partner
Partner A: The space shuttle launches at 5:00 am.
The gravity felt be the astronauts just before launch
is 9.8 m/s2. How will the force of gravity felt be
different 5 min after launch? Why?
Partner B: There are 2 identical satellites orbiting the
earth, on at a distance of 120 Km (SAT. A)and on at
a distance of 150 km (SAT B). Which satellite feels
the earths gravity the strongest? Why?
Panther Drill
Two teams are competing in a tug-of-war
contest. Team A is pulling at 4000N and
Team B is pulling at 4900N is the opposite
direction. Sketch the forces and show the
net force exerted. Which team is winning? Is
this force balanced or unbalanced?
4000N
g
g
Team A
Team B
Rope
Ground pushing up
4900N
Mass
Definition: How much matter something contains
Abbreviation: m
How it is measured: with a balance.
Unit: kilogram (kg) FOR THESE PROBLEMS MASS IS
ALWAYS IN KG
How to figure out mass (Newton’s 2nd Law: Fnet =
mass x acceleration) [Fnet = m x a]
Weight
• Definition: a force that combines (or puts
together) mass and acceleration due to Gravity
(ag) or also called the gravitational force on an
object.
• Abbreviation: W
• How it is measured: on a scale.
• Unit: Newton (N)
• How to figure it out: Weight (W) = mass (m) x
acceleration due to gravity (ag) [w=m x ag]
Calculations
Using the formula W = m x ag we can figure out
weight or mass. g (gravity) always equals
9.8 m/s2 ,unless you are on another planet.
To find weight multiply mass by gravity [w = m x ag]
To find mass divide weight by gravity [m = w/ ag]
To find gravity, divide weight by mass [ag = w/m]
Thurs
Panther Drill
#1 What is the formula for determining weight?
a) w= ag/m
b) w= ag x m
c) w= m/ag
# 2 If a stone has a mass of 14 kg and it is thrust
down at the ground with 2 times the force of
gravity, what would be the weight of the object
as it fell.
280 N
Newtons 3rd Law
Remember that when there is an action, there is
also a re-action.
Think about it like this; when you jump on a
trampoline the trampoline exerts a force back
at you.
Newtons 3rd Law
Newton’s 3rd law says, that when 1 object exerts a
force on a 2nd object the 2nd object exerts a force
that is equal and in the opposite of the 1st force.
For every action there is a an = and opposite
reaction.
So with that being said, does that mean that the
forces are balanced?
NO
Even though the forces are = they are not
balanced because they are acting on different
objects.
Think of a swimmer, as the swimmer moves
forward the water pushes back but she still
can move.
Example Lets try
Volunteers Need 2
1 sit in rolling chair and throw the ball HARD to the
other person.
Look, the ball gets force exerted on it and moves, but
you also move a little as the ball exerts a force on
you.
Think of some other examples.
Main example
Rockets use Newton’s 3rd law,
The engine exerts a force that
pushes hot gas out the back of
the rocket, the gas exerts a
force on the rocket and
LIFT OFF
What is your weight on other planets
Classwork
1. Get your mass in pounds, and convert it to Kg:
Your wt in lbs =
Your wt in Kg
2.2
256/2.2 = 116.36
2. Determine your mass: Your wt in kg
9.8
116.36/9.8 = 26.12 kg (mass)
3. Determine your weight on other planets:
W = m x ag
Gravity on other Planets
Mercury: 3.73 m/s2
Venus: 8.93 m/s2
Jupiter: 24.92 m/s2
Neptune: 11.67 m/s2
Pluto (planetoid): .784 m/s2
Now that you have your mass figured out
determine your weight on the planets above
w/ different gravity than on earth
Which Newton’s Law applies?
A ball gets kicked and rolls along the ground. The ball
will continue to roll, at a constant velocity, unless
something stops it.
1st law
You are standing on a skateboard and push against a
wall? You roll in the opposite direction.
3rd law
The fact that if you throw a baseball and softball with
the same force the baseball will move faster.
2nd law
When you are traveling in a car and holding a
cup of coffee and the driver slows down fast,
and the coffee spills over the front edge of the
cup.
1st – Inertia
The fact that the moon helps to influence the
tides on the planet and the earth keeps the
moon from flying away.
Newtons law of gravity
When a soccer ball is sitting on the ground it will
stay there until someone kicks it.
1st law
A train starts to pull a long line of boxcars that
were sitting at rest. Since the boxcars are so
massive, they have a great deal of inertia and
it takes a large force to change their
motion. Once they are moving, it takes
a large force to stop them?
1st law
The more force hit the tennis ball with the faster
it will go
2nd law
Fri
Panther Drill
What is weight?
a) Force an object exerts due to gravity
b) The mass of an object
c) Acceleration due to gravity
What is the difference between static and kinetic
friction?
a) Static friction holds in place, while kinetic friction
only occurs when objects are moving.
b) Static and kinetic friction both resist movement,
but static requires a stronger force to overcome
c) Both a and b.
Study Guide
Use the book and your notes to complete the
study guide.