Transcript 15.02.09APWeek23

AP PHYSICS
MONDAY 15.02.09
PERIOD 3 Wk23
STANDARDS:
3D.1&.2 change in momentum happens over time and
is a vector pointing in the direction of the net force.
I –Independent Resilient Individuals
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 analyze perfectly
inelastic collisions.
Warm Up
APPLY YOUR UNDERSTANDING OF
MOMENTUM
Two eggs are dropped from the top of
the bleachers. One is inside a
container filled with a combination of
kleenex and packing materials. The
other is dropped without a container.
If the impulse of each egg due to the
ground is the same, why does one egg
break and one egg survive.
Agenda:
1. Warm Up
2. Review HW #3
3. Perfectly Inelastic Collisions Notes
4. Inelastic Collisions Guided Practice
Homework
MAP#4
AP PHYSICS
TUESDAY 15.02.10
STANDARDS:
3D.1&.2 change in momentum happens over time and
is a vector pointing in the direction of the net force.
I –Independent Resilient Individuals
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 demonstrate
understanding of how elastic collisions
affect the momentum of the object
Agenda:
1. Warm Up
2. Turn in HW
3. Elastic Collisions Notes
4. MAP#5
Warm Up
Two skydivers jump from a plane one
after another in flying suits where they
are able to turn most of their
gravitational force into horizontal
motion. For this problem ignore the
motion in the y direction. The first 65
kg skydiver jumps and is able to reach
a maximum speed of 35 m/s. The
second slightly smaller 60 kg diver is
able to reach a faster 40 m/s speed.
Skydiver 1’s parachute doesn’t work
so skydiver 2 tries to come up and
grab skydiver 1 before letting the
working shoot go. What will be their
new speed after skydiver 2 catches
skydiver 1, but before they pull the
working parachute.
Homework
Map#5
AP PHYSICS
WEDNESDAY 15.02.11
Standards: 3D.1&.2 change in momentum happens
over time and is a vector pointing in the direction of the
net force.
I –Independent Resilient Individuals
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
Warm Up
A juggler juggles 11 balls at one time.
Each ball has a mass of 0.20 kg. Two
of these balls collide elastically. The
first ball moves away from the collision
with a velocity of 3.0 m/s to the right,
and the second ball moves away with
a velocity of 4.0 m/s to the left. If the
first ball’s velocity before the collision
was 4.0 m/s to the left, what was the
velocity of the second ball before the
collision?
Learning Goal: SWBAT apply
conservation of momentum & energy to
collisions
Agenda:
1. Warm Up
2. Review Hw#4&#5
3.
Collision FRQ
Homework
Map#6
AP PHYSICS
THURSDAY 15.01.29
STANDARDS:
3D.1&.2 change in momentum happens over time and
is a vector pointing in the direction of the net force.
I –Independent Resilient Individuals
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
Warm Up
A 2kg hockey puck travels across a
fairly smooth concrete surface with an
initial velocity of 22 m/s. If 10 N of
friction acts on the puck for 3
seconds, what is its impulse? How far
did the hockey puck travel during this
time?
Learning Goal: SWBAT demonstrate
understanding of momentum concepts
through a collaborative AP problem
performance exam.
Agenda:
1. Warm Up
2. Review HW#5
3. Collaborative Performance Exam
Homework
Finish MAP 4-6 and Test
Corrections
AP PHYSICS
FRIDAY 15.01.30
STANDARDS:
3D.1&.2 change in momentum happens over time and
is a vector pointing in the direction of the net force.
I –Independent Resilient Individuals
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
Warm Up
Describe a scenario with specific
objects doing specific things (don’t
be general at all!) where
a. momentum & mechanical
energy are conserved
b. just mechanical energy is
conserved, and
c. just momentum is conserved
Learning Goal: SWBAT verify
conservation of momentum and energy
through experimentation with carts and
masses
Agenda:
1. Warm Up
2. Guided Practice – AP Problem
3. Energy loss in inelastic ollision
4. MAP #5
Homework
MAP #7
Momentum & Collisions Test Thursday
#1 VERTICAL CIRCLE LAB
Using a timer, triple beam balance, a mass on a string, and a meter stick,
experimentally find the Tension in the string at the top of the circle and at the
bottom.
Hint: The following equations should help you determine which quantities you should
measure, Fnet=ma, ac=v2/r, v=2πr/T . Free body diagrams and Free body
diagram expressions, will make the process much easier also.
GRAVITATIONAL FORCE
F=Gm1m2/r2, Fc=mv2/r,
MOMENTUM & IMPULSE MAP#1
1.
In 1987, Marisa Canofoglia, of Italy, roller-skated at a record-setting speed of 40.3 km/h. If the magnitude
of Canofoglia’s momentumwas 6.60x102 kgm/s, what was her mass?
2.
One of the smallest planes ever flown was the Bumble Bee II, which had a mass of 1.80x10 2 kg. If the
pilot’s mass was 7.0x101 kg, what was the velocity of both plane and pilot if their momentum was 2.08x10 4
kgm/s to the west?
3.
Among the largest passenger ships currently in use, the Norway has been in service the longest. The
Norway is more than 300 m long, has a mass of 6.9x107 kg, and can reach a top cruising speed of 33
km/hr. Calculate the magnitude of the ship’s momentum while cruising.
4.
A bronze statue of Buddha was completed in Tokyo in 1993. The statue is 35m tall and has a mass of
1.00x106 kg. Suppose this statue were to be moved to a different location . What is the magnitude of the
impulse that must act on the statue in order for the speed to increase from 0m/s to 0.20 m/s? If the
magnitude of the net force acting on the statue is 12.5 kN, how long will it take for the final speed to be
reached?
5.
In 1992, Dan Bozich of the United States drove a gasoline-powered gocart at a speed of 125.5 km/h.
Suppose Bozich applies the brakes upon reaching this speed. If the combined mass of the go-cart and
driver 2.00x102kg, the decelerating force is 3.60x102N opposite the cart’s motion, and the time during
which deceleration takes place is 10.0s. What is the final speed of Bozich and the go-cart?
6.
FORCE & IMPULSE MAP#2
1.
(#4) The first human-made satellite, Sputnik I, has a mass of 83.6 kg and a
momentum with a magnitude of 6.63x105 kgm/s. What was the satellite’s
speed?
2.
(#6) In 1994, a tower 22.13 m tall was built of Lego blocks. Suppose a block
with a mass of 2.00 g is dropped from the top of this tower. Neglecting air
resistance, calculate the block’s momentum at the instant the block hits the
ground.
3.
(6) The “human cannonball” has long been a popular—and extremely
dangerous—circus stunt. in order for a 45 kg person to leave the cannon with the
fastest speed yet achieved by a human cannonball, a 1.6x103N force must be
exerted on that person for 0.68s. What is the record speed at which a person
has been shot from a circus cannon?
4.
(2) In 1920, a 6.5x104kg meteorite was found in Africa. Suppose a meteorite
with this mass enters Earth’s atmosphere with a speed of 1.0 km/s. What is the
change in the meteorite’s momentum if the average constant force of -1.7x106N
acts on the meteorite for 30.0s? How far does the meteorite travel during this
time.
5.
(4) The record for the smallest dog in the world belongs to a terrier who had a
mass of only 113 g. Suppose this dog runs to the right with a speed of 2.00 m/s
when it suddenly sees a mouse. The dog becomes scared and uses its paws to
bring itself to rest in 0.80s. What is the force required to stop the dog? What is
the dog’s stopping distance?
CONSERVATION OF MOMENTUM GUIDED
PRACTICE
1. Kangaroos are good runners that can sustain a speed of 56 km/h (15.5 m/s).
Suppose a kangaroo is sitting on a log that is floating in a lake. When the kangaroo
gets scared, she jumps off the log with a velocity of 15 m/s toward the bank. The
log moves with a velocity of 3.8 m/s away from the bank. If the mass of the log is
250 kg, what is the mass of the kangaroo?
CONSERVATION OF MOMENTUM MAP#3
1.
The largest grand piano in the world is really grand. Built in London, it has a mass of
1.25x103 kg. Suppose a pianist finishes playing this piano and pushes herself from
the piano so that she rolls backwards with a speed of 1.4 m/s. Meanwhile, the piano
rolls forward so that in 4.0 s it travels 24 cm at constant velocity. Assuming the stool
that the pianist is sitting on has a negligible mass, what is the pianist’s mass?
2.
With a mass of 114 kg, Baby Bird is the smallest monoplane ever flown. Suppose
the Baby Bird and pilot are coasting along the runway when the pilot jumps
horizontally to the runway behind the plane. The pilot’s velocity upon leaving he
plane is 5.32 m/s backward. After the pilot jumps from the plane, the plane coasts
forward with a speed of 3.40 m/s. If the pilot’s mass equals 60.0 kg, what is the
velocity of the plane and pilot before the pilot jumps.
3.
The largest frog ever found was discovered in Cameroon in 1989. The frog’s mass
was nearly 3.6 kg. Suppose this frog is placed on a skateboard with a mass of 3.0
kg. The frog jumps horizontally off the skateboard to the right, and the skateboard
rolls freely in the opposite direction with a speed of 2.0 m/s relative to the ground. If
the frog and skateboard are initially at rest, what is the initial horizontal velocity of
the frog?
4.
In 1994, ,a pumpkin with a mass of 449 kg was grown in Canada. Suppose you want
to push a pumpkin with this mass along a smooth, horizontal ramp. You give the
pumpkin a good push, only to find yourself sliding backwards at a speed of 4.0 m/s.
How far will the pumpkin slide 3.0 s after the push? Assume your mass to be 60.0
kg.
PERFECTLY INELASTIC COLLISIONS
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Before
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vbr
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After
Elastic is like a rubber band. It stretches, it pushes back on you or bounces back, like a
spring. So an inelastic collision is a collision where there is no bounce. In this case, there is a
crunch.
-Momentum is conserved during inelastic collisions, even though mechanical energy is not
Why do you think mechanical energy is
not conserved in inelastic collisions? Where does the
energy go?
conserved in this situation.
ELASTIC COLLISIONS
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Before
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After
In elastic collisions the two objects bounce off each other with no mechanical energy lost to
heat, sound, or deformation of the object.
When no external force is present momentum is conserved so:
mrvri+mbvbi=mrvrf+mvbf
PERFECTLY INELASTIC COLLISION MAP#4
1.
(1) Zorba, an English mastiff with a mass of 155 kg, jumps forward horizontally at a speed of
6.0 m/s into a boat that is floating at rest. After the jump, the boat and Zorba move with a
velocity of 2.2 m/s forward. Calculate the boat’s mass.
2.
(3)The world’s largest guitar was built by a group of high school students in Indiana. Suppose
that this guitar is placed on a light car. The cart and guitar are then pushed with a velocity of
4.48 m/s to the right. One of the students tries to slow the cart by stepping on it as it passes
by her. The new velocity of the cart, guitar, and student is 4.00 m/s to the right. If the
student’s mass is 54 kg, what is the mass of the guitar? Assume the mass of the cart is
negligible.
3.
(7) In 1990, Roger Hickey of California attained a speed of 89 km/h while standing on a
skateboard. Suppose Hickey is riding horizontally at his stand-up speed when he catches up to
another skateboarder, who is moving at 69 km/h in the same direction. If the second
skateboarder steps sideways onto Hickey’s skateboard, the two riders move forward with a new
speed. Calculate this speed, assuming that both skateboarders have equal, but unknown,
masses and that the mass of the skateboard is negligible.
4.
(8) The white shark is the largest carnivorous fish in the world. The mass of a white shark can
be as great as 3.0x103 kg. In spite of (or perhaps because of) the mass and ferocity of the
shark, it is prized by commercial and sports fishers alike. Suppose Joe, who is one of these
fishers, goes to a cliff that overlooks the ocean. To see if the sharks are biting, Joe drops a
2.5x102 kg fish as bait into the ocean below. As it so happens, a 3.0x10 3 kg white shark is
prowling the ocean floor just below the cliff. The shark sees the bait, which is sinking straight
down at a speed of 3.0m/s. The shark swims upward with a speed of 1.0 m/s to swallowed the
bait?
MAP#7 KINETIC ENERGY IN INELASTIC
COLLISIONS
1.
(1)The hog-nosed bat is the smallest mammal on Earth: it is about the same size as a
bumblebee and has an average mass of 2.0 g. Suppose a hog-nosed bat with this mass
flies at 2.0 m/s when it detects a bug with a mass of 0.20 g flying directly toward it at 8.0
m/s. What fraction of the total kinetic energy is dissipated when it swallows the bug?
2.
(2)The heaviest wild lion ever measured had a mass of 313 kg. Suppose this lion is
walking by a lake when it sees an empty boat floating at rest near the shore. The curious
lion jumps into the boat with a speed of 6.00 m/s, causing the boat with the lion in it to
move away from the shore with a speed of 2.50 m/s. How much kinetic energy is
dissipated in this inelastic collision.
3.
(3)The cheapest car ever commercially produced was the Red Bug backboard, which sold
in 1922 in the United States for about $250. The car’s mass was only 111 kg. Suppose
two of these cars are used in a stunt crash for an action film. If one car’s initial velocity is
9.00 m/s to the right and the other car’s velocity is 5.00 m/s to the left, how much kinetic
energy is dissipated in the car crash?
4.
(6)There was a domestic cat in Australia with a mass of 21.3 kg. Suppose this cat is
sitting on a skateboard that is not moving. A 1.80x10 -1 kg treat is thrown to the car.
When the cat catches the treat, the cat and the skateboard move with a speed of
6.00x10-2 m/s. How much kinetic energy is dissipated in the process? Assume onedimensional motion.
MAP#5 ELASTIC COLLISIONS
1.
(1) The moon’s orbital speed around the Earth is 3.680x10 3km/h. Suppose the moon
suffers a perfectly elastic collision with a comet whose mass is 50.0 percent that of the
moon. (A partically inelastic collision would be a much more realistic event.) After the
collision, the moon moves with a speed of -4.40x102km/h, while the comet moves away
from the moon at 5.740x103km/hr. What is the comet’s speed before the collision?
(Solve using conservation of momentum & check your answer using conservation of
energy.)
2.
(3) The first astronaut to walk in outer space without being tethered to a spaceship was
Capt. Bruce McCandless. In 1984, he used a jet backpack which cost about $15 million
to design, to move freely about the exterior of the space shuttle Challenger. Imagine two
astronauts working in outer space. Suppose they have equal masses and accidentally run
into each other. The first astronaut moves 5.0 m/s to the right before the collision and 2.0
m/s to the left afterwards. If the second astronaut moves 5.0 m/s to the right after the
perfectly elastic collision, what was the second astronaut’s initial velocity?
3.
(4) Speeds as high as 273 km/h have been recorded for golf balls. Suppose a golf ball
whose mass is 45.0 g is moving to the right at 273 km/h and strikes another ball that is at
rest. If after the perfectly elastic collision the golf ball moves 91 km/h to the left and the
other ball moves 182 km/h to the right, what is the mass of the second ball.
ELASTIC COLLISIONS – GUIDED PRACTICE
Jana Novotna of what is now the Czech Republic had the strongest serve among her
fellow tennis players in the early 90’s. In 1993, she sent the all flying with a
speed of 185 km/hr. Suppose a tennis ball moving to the right at this speed hits
a moveable target of unknown mass. After the one-dimensional, perfectly elastic
collision, the tennis ball bounces to the left with a speed of 80 km/hr. If the
tennis ball’s mass is 5.70x10-2 kg, what is the target’s mass?