Transcript 15.02.09PhysicsWeek23

Monday, February 9, 2015
Physics & Honors Physics
E-Effective Communicators
Standards: HS-PS2-1 Analyze data to support the claim
that Newton’s second Law of motion describes the
mathematical relationship among the net force on a
macroscopic object, its mass, and its acceleration
RST.11-12.4 Meaning of symbols, key terms, technical
jargon
WHST.11-12.7: research to aid in problem solving
Learning Goal: SWBAT predict and identify
how the gravitational force works for objects
on earth.
Agenda
1. Warm Up
2. Review HW#5
3. #42 Centripetal Force Lab Reflection
4. Bill Nye Gravity on Earth:
https://www.youtube.com/watch?v=y9kP8t0y2
t4
WEEK 23
Warm Up
A 0.5 kg yoyo spins in circles
of radius 0.3m. A student
provides an unknown
amount of centripetal force
to make it spin. The student
spins the yoyo 10 times in 30
seconds. Find T, vs, and F c
Homework
G#1
Notebooks
P.7 - Monday
P.5 – Tuesday
P.4 - Wednesday
P.2- Thursday
P.1- Friday
Monday February 9, 2015
I –Independent Resilient Individuals
Standards: HSPS21-Analyze data to support the claim that
Newton’s second law of motion describes the mathematical
relationship among the net force on a macroscopic object, its
mass, and its acceleration.
RST.11-12.9 Synthesize information from a range of sources
into coherent understanding of a process, phenomenon, or
concept,…
Warm Up
A 0.5 kg yoyo spins in
circles of radius 0.3m. A
student provides an
unknown amount of
centripetal force to make
it spin. The student spins
vthe yoyo 10 times in 30
seconds. Find T, vs, and F
c
WHST.11-12.7: research to aid in problem solving
Learning Goal: SWBAT find the speed of
a ball on a string undergoing centripetal
motion
Agenda:
1. Warm Up
2. Review HW #5
3. Finish Lab Table - 10 min
4. Lab Reflection
Period 1
Homework
C#5
Tuesday February 9, 2015
I –Independent Resilient Individuals
Standards: HSPS21-Analyze data to support the claim that
Newton’s second law of motion describes the mathematical
relationship among the net force on a macroscopic object, its
mass, and its acceleration.
RST.11-12.9 Synthesize information from a range of sources
into coherent understanding of a process, phenomenon, or
concept,…
WHST.11-12.7: research to aid in problem solving
Learning Goal: SWBAT find the speed of
a ball on a string undergoing centripetal
motion
Agenda:
1. Warm Up
2. #42 Centripetal Force Lab Reflection
3. Bill Nye Gravity on Earth:
https://www.youtube.com/watch?v=y9
kP8t0y2t4
Warm Up
If you spin a 4 kg mass
on a string with a
radius of 2 m 10 times
in 20 seconds, find the
vperiod of the motion,
the speed of the mass,
and the centripetal
force acting on it.
Period 1
Homework
NA
Tuesday, February 10, 2015
Physics & Honors Physics
E-Effective Communicators
Standards: HS-PS2-1 Analyze data to support the claim
that Newton’s second Law of motion describes the
mathematical relationship among the net force on a
macroscopic object, its mass, and its acceleration
RST.11-12.4 Meaning of symbols, key terms, technical
jargon
WHST.11-12.7: research to aid in problem solving
Warm Up
a. What causes gravity?
b. Name everything you
can think of that affects
the strength of the
gravitational force
between two objects.
Learning Goal: SWBAT understand how
gravitational force works on earth and
connect it to the workings of gravitational
force in the stars
Agenda
1. Warm Up
2. Finish Bill Nye Q’s and Discussion
3. Gravitational Force Notes
4. Gravitational Force #43 activity
Homework
G#1
Tuesday, February 10th, 2015
I –Independent Resilient
Individuals
Standards: HS-PS2-1 Analyze data to
support the claim that Newton’s second Law
of motion describes the mathematical
relationship among the net force on a
macroscopic object, its mass, and its
acceleration
RST.11-12.4 Meaning of symbols, key terms,
technical jargon
WHST.11-12.7: research to aid in problem
solving
Warm Up
If a 2 kg object spins in a circle
100 times in 12 seconds, what is
its period? draw it and solve it.
Learning Goal: SWBAT understand PERIOD
how gravitational force works on earth
and connect it to the workings of
gravitational force in the stars
Agenda:
1. Warm Up
2. Centripetal Force Notes
3. Measuring Period Activity #39
4. Create an experimental procedure ot
find the centripetal acceleration of
1
Homework
G#1
Wednesday February 11th, 2015
I –Independent Resilient Individuals
Standards: HSPS21-Analyze data to support the claim that
Newton’s second law of motion describes the mathematical
relationship among the net force on a macroscopic object, its
mass, and its acceleration.
RST.11-12.9 Synthesize information from a range of sources into
coherent understanding of a process, phenomenon, or concept,…
WHST.11-12.7: research to aid in problem solving
Learning Goal: SWBAT find the gravitational
force between two objects
Agenda:
1. Warm Up
2. #43 Finish Bill Nye Video/Activity
3. #44 Finish Gravitational activity
4. #45 Take Notes, practice finding the
gravitational force between two objects
with mass
Warm Up
A 0.5 kg golf ball and a
30 kg bowling ball are
dropped from 1000
feet in the air? What is
the magnitude of the
gravitational force
exerted by the objects
on the earth? Will
these forces
significantly affect the
earth’s motion?
Homework
G#2,GH#2
Wednesday February 11th, 2015
I –Independent Resilient Individuals
Standards: HSPS21-Analyze data to support the claim that
Newton’s second law of motion describes the mathematical
relationship among the net force on a macroscopic object, its
mass, and its acceleration.
RST.11-12.9 Synthesize information from a range of sources
into coherent understanding of a process, phenomenon, or
concept,…
WHST.11-12.7: research to aid in problem solving
Learning Goal: SWBAT understand how
gravitational force works on earth and
connect it to the workings of gravitational
force in the stars
Agenda:
1. Warm Up
3. #44 Gravitational Force Notes
4.
Warm Up
What do you know
about gravity?
Tell me at least 3
things.
What don’t you
know about gravity?
Tell me one thing. #
each thing for credit
PERIOD 1
Homework
G#1
Thursday, February
12th, 2015
E-Effective Communicators
Standards: Analyze data to support the claim
that Newton’s second law of motion describes the
mathematical relationship among the met force
on a macroscopic object, its mass, and its
acceleration (CENTRIPETAL)
RST.11-12.1 cite specific textual evidence…
WHST.11-12.7: research to aid in problem
solving.
Warm Up
Find the force of gravity
between a 2 & 4 kg mass
that are 20 m apart? Is the
gravitational force between
them strong?
Learning Goal: SWBAT understand the
timeline for the science fair.
Agenda:
1. Warm Up
2. Review Hw #1
3. Work on assignment #45
Homework
G#3
Thursday, February 12th, 2015
Physics & Honors Physics
E-Effective Communicators
Warm Up
a. What causes gravity?
b. Name everything you can
Standards: HS-PS2-1 Analyze data to support the claim that think of that affects the
Newton’s second Law of motion describes the
strength of the gravitational
mathematical relationship among the net force on a
force between two objects
macroscopic object, its mass, and its acceleration
RST.11-12.4 Meaning of symbols, key terms, technical jargon
WHST.11-12.7: research to aid in problem solving
Learning Goal: SWBAT understand the
timeline for the science fair.
Agenda
1. Warm Up
2. Answer Mousetrap Car Report Questions
3. Review Hw 1 & Gravity #44
4. Watch Bill Nye Intro to Gravity #43
5. Learn about science fair & pick groups.
Period 1
Homework
G#1
Friday, February 13th,
2015
I –Independent Resilient Individuals
Standards: HS-PS2-1 Analyze data to
support the claim that Newton’s second Law
of motion describes the mathematical
relationship among the net force on a
macroscopic object, its mass, and its
acceleration
RST.11-12.4 Meaning of symbols, key terms,
technical jargon
Learning Goal: SWBAT
Agenda:
1. Warm Up
2. #46 Acceleration at SG & Everest
3. HW G#4
Warm Up
Find the gravitational force
between a 2000 kg object and
a 10,000 kg object if they are 10
m apart from each other.
Homework
Mousetrap Car Writeup
Redo Due Tuesday
G#4
Gravity & Centripetal
Motion Tests next week
Warm Up
Find Mr. A’s weight on earth
and on mars (amars=3.9 m/s2) if
his mass is 65 kg.
Friday, February 13th, 2015
P-Problem Solvers
Standards: HS-PS2-1 Analyze data to
support the claim that Newton’s second Law
of motion describes the mathematical
relationship among the net force on a
macroscopic object, its mass, and its
acceleration
RST.11-12.4 Meaning of symbols, key terms,
technical jargon
WHST.11-12.7: research to aid in problem
solving
Learning Goal: SWBAT
Agenda:
1. Warm Up
2. Review Hw #1 CW#44
3. Stamp HW
4. #45 Notes
5. Work on assignment #45
Homework
G#2
Notebooks Due P.1Friday
Centripetal Motion &
Gravity Test Next Week
Period 1
Equations:
Symbols, units and
equations Sheet
Constant Velocity
v=
Dx
Dt
d
v
=
Dy = y f - yi s t
Dx = x f - xi
Constant Acceleration
a=
Dv Dv = v - v Dy = y - y
f
i
f
i
Dt
The Two equations of Motion Dx = x f - xi
Horizontal Direction
1.
v f = vi + at
2.
1
Dx = vi t + at 2
2
The Two equations of Motion
Vertical Direction
ag=-9.8m/s2
Concept
symbol
units
distance
d
m
displacement
Δx or Δy
m
speed
vs
m/s , km/hr
velocity
v
m/s, km/hr
acceleration
a
m/s2, km/hr2 or
N/kg
mass
m
kg
Force
F
N or kgm/s2
Forces
Fnet = ma
Fg = W = mg
v f = vi + agt
g=9.8m/s2
1
Dy = vi t + agt 2
2
Fa on b = -F b on a
Lab/Engineering Write Up Rubric
Section
2
1
0
Question/Problem
The Lab Question/Design
Problem is Stated
Your question/problem solved
does not fit with your
experiment
Missing
Materials and
Procedures/Design Process
The procedures/Design
Process is written step by step
in complete sentences and the
materials are clearly listed.
Procedures/Design Process
incomplete or too general or
Materials are missing
Procedure/Design Process is
missing
Data Collection
Contains a table and a graph
that represents the data
accurately and is labeled
correctly
Data table and/or graph is
done incorrectly or labeled
incorrectly
Either data table or graph is
missing.
Calculations
Students have all calculations
completed, with work shown,
and they are correct.
At least half of the calculations
are done correctly
1 or more calculations are
missing and/or less than half
are done correctly and/or work
is not shown
Analysis
The student gives evidence
from their lab data why their
hypothesis is true, false, or
inconclusive, or why they
solved or did not solve their
design problems.
The lab write up gives no
evidence from their lab data to
support evaluate their
hypothesis
The hypothesis/design
problem is not evaluated.
Conclusion
The conclusion includes a
summary of your lab results,
which discusses any errors in
your experiment or
difficulties/limitations of your
building process.
Sources of error in your
experiment or
limitations/difficulties in your
design process are not
discussed.
This section is absent or it is
discussed only in the analysis
section
CH#5 Finding Centripetal Force.
• Use both v=2πr/T and Fc=mv2/r to solve
the following problems.
1. Find the centripetal force of a 1 kg object swinging horizontally with a radius of
1 m and a period of 1s?
2. Find the centripetal force of a 4 kg object swinging horizontally with a radius of
4 m and a period of 0.5s?
3. A 2200 kg car drives on a circular track. If it takes 300s (5 min) to make one lap
around the track of radius 2000 m, what is the centripetal Force keeping the car
on the track?
4. A wrecking ball on a crane as has mass of 20,000 kg. The crane’s controls
malfunction and lock causing the crane and wrecking ball to spin. If the radius
of the circle made by the wrecking ball is 500 m, and the period of the spin was
20s, what Centripetal Force must the crane provide so that the wrecking ball will
continue spinning and not break and cause chaos in the city?
5. **The centripetal Force caused by a ball swinging on a mass is 200 N. If the
mass of the object is 2 kg, and the radius is 20m what is the period of the
centripetal motion?
C#5 Finding Centripetal Force.
• Use both v=2πr/T and Fc=mv2/r to solve
the following problems.
1. Find the centripetal force of a 1 kg object swinging horizontally with a radius of
1 m and a period of 1s?
2. Find the centripetal force of a 4 kg object swinging horizontally with a radius of
4 m and a period of 0.5s?
3. A 2200 kg car drives on a circular track. If it takes 300s (5 min) to make one lap
around the track of radius 2000 m, what is the centripetal Force keeping the car
on the track?
4. A wrecking ball on a crane as has mass of 20,000 kg. The crane’s controls
malfunction and lock causing the crane and wrecking ball to spin. If the radius
of the circle made by the wrecking ball is 500 m, and the period of the spin was
20s, what Centripetal Force must the crane provide so that the wrecking ball will
continue spinning and not break and cause chaos in the city?
#41 Centripetal Motion Lab
Objective: Find the mass of the object spinning in
circles.
r
1. Fill in the table below. Setup will be done together.
mb
Mass of bronze weight:_______kg
Tria
l
mball
mclip
W
(kg)
(kg)
(total)
(N)
total
time
(s)
#
rev
T(s)
F(N)
rstr+b
v
all (m)
(m/s)
a
(m/s2)
1
2
3
binder clip
3. Graph F vs. r (the right 2 columns), find the best fit
line, the slope, and the equation of the line.
F(N)
W=mg
a (m/s2)
4. slope = mass of ball so we will compare the mass of the ball measured with the triple
beam balance with the slope of our line.
mball - mslopeofline
%error =
mball
x100%
#41 Centripetal Motion Lab
Objective: Find the mass of the object spinning in circles.
Theory: In this experimental setup gravity is responsible for the
circular motion of the mass. Therefore if we change the gravitational
force that the mass experiences, but keep the radius constant we will
change the centripetal acceleration of the object. We can ultimately
use this data to find the mass of the object.
Trial
mobj
mclip
mbron
(kg)
(kg)
ze
weight
W=Fc
(N)
(kg)
total
time
(s)
# rev
T(s)
r
mo
ac
rstr+ba
v
ll (m)
(m/s)
(m/s2)
1
2
binder clip
3
3. Graph Fc vs. ac , find the best fit line, the slope, and
the equation of the line.
Fc(N)
bronze
weight
ac (m/s2)
4. slope = mass of ball so, measure the mass of the ball with a triple beam balance and
then compare it using the following % error equation.
m -m
%error =
ball
slopeofline
mball
x100%
Centripetal Motion Lab Discussion &
Reflection #42
Why did we do this lab?
1.What difficulties did you encounter in the lab?
2. What aspects of the lab seemed to be the most inaccurate?
3. Why did you use a straw in this lab instead of just holding the string and swinging
it?
4. How would clamping your fingers over the straw and string affect your data?
5. Explain the process you used to find the period of the centripetal motion.
6. If you increased the radius of your circle, what happened to the centripetal Force?
7. What does v2/r mean? How do you know?
8.Fc=mv2/r is a variation of which important equation we already learned.
#44 Newton’s Universal
Law of Gravitation
Fearth
Fperson
Earth
• This is an extension of Newton’s 3rd Law: For
every action there is an equal and opposite
reaction.
• Gravity is the force of attraction between
objects with mass.
• Gravity is always pushing us (or exerting Force on
us) towards the center of the earth
We are also exerting an equal and opposite Force on the earth.
Newton’s Law of Universal Gravitation #44
2kg
1.
2.
2kg
2kg
3.
4.
2kg
2kg
2kg
4kg
4kg
a. Do you think a larger mass will make the gravitational force weaker or
stronger?
b. Do you think a greater distance between the objects will make the gravitational
force weaker or stronger? Ultimately predict which single factor has a greater
impact on the gravitational force, the mass of an object or the distance between
the objects?
c. Rank gravitational force of 1-4, highest to lowest
#45 Newton’s Universal
Law of Gravitation
• Specifically this law says:
• F=Gm1m2
---------r2
• Where G is the gravitational
constant 6.67x10-11 Nm2/kg2
• m1 and m2 are any two objects with
a mass.
• r is the distance between the center
of the two objects
• How would you find out whether or
not you use Fg=W=mg or
Fg=Gm1m2/r2
m1
m2
r
#45 Practice
Find the Gravitational Force of Each. Rank them in order from largest to smallest.
2kg
2kg
1m
1.
2kg
2kg
2.
3m
3.
2kg
1m
4kg
4kg
4.
2kg
3m
Gravitational Force # G1
1.
2.
3.
4.
5.
6.
7.
What if any, is the difference between weight and
Gravitational Force?
An apple falls from a tree. If the gravitational Force on the
apple is 10N, how much force is the apple pushing the earth
with?
A 65 kg skydiver is in freefall. What is the Gravitational Force
that the earth is putting on the skydiver? What is the direction
of this Force.
From problem 3. What is the gravitational Force that the
skydiver is putting on the earth? What direction is this Force?
With how much Force will Gravity attract a 2000 kg object?
How much would a 90 kg person weigh on Mars?
(ag=3.9m/s2)
From Problem 6. What is the Gravitational Force between
the person and the planet?
Newton’s Law of Gravitation
Practice HG#2
Use this equation for the following problems:
F=(Gm1m2)/r2
G=6.67x10-11Nm2/kg2
1. Find Fg.
M1=2kg
M2=7kg
R=500m
2. Find Fg.
m1=4x104kg
m2=8x106kg
r=4x104m
3. Find Fg.
M1=5x1024 kg
M2=9x1018 kg
R=3x105 m
4. Find R.
M1=5x105 kg
M2=4x1010 kg
Fg= 4x103 N
5. A 6kg object and a 20 kg object are separated by 50 m. What is the
gravitational Force between the two masses?
6. From problem 5, how fast will the 6kg object accelerate towards the 20 kg
object?
Newton’s Law of Gravitation
Practice G#2
Use this equation for the following problems:
F=(Gm1m2)/r2
G=6.67x10-11Nm2/kg2
a. Find Fg.
M1=2kg
M2=7kg
R=500m
b. Find Fg.
m1=4x104kg
m2=8x106kg
r=4x104m
c. Find Fg.
M1=5x1024 kg
M2=9x1018 kg
R=3x105 m
1. A 6kg object and a 20 kg object are separated by 50 m. What is the
gravitational Force between the two masses?
Gravitational Force
Practice G#3
1.
2.
3.
4.
What is the force of attraction (gravitational force) between
two people if one person is 85 kg and the other is 72 kg and
the two people are 2 m away from each other?
If one person (70kg) is in Los Angeles and another(70kg) is in
Bejing 1x107 m away, what is the force of attraction between
the two people?
Find the force of gravity exerted on a 55 kg (121 lb) person
lying 0.1 meters below a 200,000kg (90,000 lbs) train.
If an astronaut landed on the surface of Mars, what would
the Force of Gravity be on a person with a mass of 75kg
(165lbs) if Mars has a mass of 6.42x1023kg and a radius of
3.37x106m?
Gravity & Circular
Motion
From learning about Gravity, we know:
1. Objects in space with a large enough speed will
orbit the earth or other large objects at a constant
speed.
2. As long as nothing causes the object to lose speed
it will orbit the earth forever.
3. The object stays at the same distance from the
earth throughout the circular orbit.
From learning about Centripetal Motion, we know:
1. The speed of the object will always be
perpendicular to the direction of the force of
gravity.
2. When Gravity makes objects orbit other objects in
a circle, gravity is acting as a Centripetal Force.
#43 Bill Nye Video
Questions
1. What does gravity do? Give 3 examples
2. Who was the first scientist to experiment with falling
objects?
3. What did this scientist discover?
4. What will happen to a feather and hammer if you
dropped it on earth? What happened on the
moon?
5. Challenge: How can gravity be responsible for
making things fall to the ground and for making
planets orbit around the sun? Give an
explanation.
#46 Gravitational Force & Acceleration in South Gate
Now that we understand what gravitational force is and how to calculate it,
we are going to extend our new knowledge to find the exact acceleration
due to gravity in South Gate and we’ll compare it to Mount Everest.
southgate
mmr.a
Theory: Gravity is supposed to be weaker in
South Gate than Mt. Everest because of Mt.
Everest’s higher elevation. Does it really
make much difference though?
- We know how to calculate the force of
gravity between 2 objects, for example Mr. A
and the Earth.
- What can we do with that force find
out the value what we consider gravity, g=
9.8m/s2 ?
- Hopefully you’re thinking Fnet=ma. If
we put the gravitational force into this
equation in place of Fnet, then the a will be
acceleration due to gravity, or g.
(Don’t Forget to convert km ->m)
rsg
rev
mearth
everest
mmr.a
Instructions:
a. Create a data table with mmr. , mearth, rsg, rev Fsg,
Fev, asg, aev
b. Look up the mass and radius of the earth
online or in one of the textbooks.
c. Look up the elevation (height) above sea level
for South Gate and Mt. Everest.
d. Find the distance between the center of the
earth & the center of Mr. A (height 1.92m, mass
65kg) if he were in South Gate or Mt. Everest.
e. Calculate the Force of gravity in South Gate &
Everest
f. Calculate the Acceleration due to gravity in
South Gate and Everest.
GH#4 Gravitational Force & Acceleration
use F=Gm1m2/r2 & Fnet=ma to solve the problems below along with
G=6.67x10-11 Nm2/kg2
a. -
-
me=5.97x1024kg
mperson =72 kg
r=6.371x106 m
Fg=?
ag=?
b. -
-
me=5.97x1024kg
mcar =1000 kg
r=6.371x106 m
Fg=?
ag =?
c. -
-
me=5.97x1024kg
minsect = 0.001 kg
r=6.371x106 m
Fg=?
ag =?
1. After calculating Fg and ag for a,b, & c , what pattern did you notice?
2. What variable in a,b, & c did not affect the how fast the object would accelerate
if it was falling to the ground?
3. The class takes a trip to Griffith park. At Griffith Park’s highest point it is 495.3
m. The mass and radius of the earth are 5.97x1024kg and 6.371x106 m. What is
the acceleration due to gravity if an object of any mass is placed at that point?
(Remember your answer from #2, knowing that will help you solve this)
G#4 Gravitational Force & Acceleration
use F=Gm1m2/r2 & Fnet=ma to solve the problems below along with
G=6.67x10-11 Nm2/kg2
a. -
-
me=5.97x1024kg
mperson =72 kg
r=6.371x106 m
Fg=?
ag=?
b. -
-
me=5.97x1024kg
mcar =1000 kg
r=6.371x106 m
Fg=?
ag =?
c. -
-
me=5.97x1024kg
minsect = 0.001 kg
r=6.371x106 m
Fg=?
ag =?
1. After calculating Fg and ag for a,b, & c , what pattern did you notice?
2. What variable in a,b, & c did not affect the how fast the object would accelerate
if it was falling to the ground?
3. The class takes a trip to Griffith park. At Griffith Park’s highest point it is 495.3
m. The mass and radius of the earth are 5.97x1024kg and 6.371x106 m. What is
the acceleration due to gravity if you place an object
a. of 1kg mass at that point?
b. of 100 kg mass at that point?
c. of your mass of at that point?