Transcript 15.01.20APWeek20

AP PHYSICS
TUESDAY 15.01.20
PERIOD 3
STANDARDS:
f3A describing forces with velocity, acceleration, etc.
Warm Up
What is the gravitational field
produced by objects of mass 100g,
2x104kg, 9x1011kg, and 3x1020kg at
a distance of 1km?
g=Gm/r2
I –Independent Resilient Individuals
RST.11-12.9 Synthesize information from a range of
sources into coherent understanding of a process,
phenomenon, or concept,…
Learning Goal: SWBAT review centripetal
motion & gravity
Agenda:
1. Warm Up – Answers: 6.67x10-18 N/kg, 1.3x1012N/kg, 6x10-5 N/kg, 2x104 N/kg
2. Homework will be collected on Wednesday
3. Finish Gravity #2
4. HW CAP #9
Homework
CAP #9
AP PHYSICS
WEDNESDAY 15.01.21
STANDARDS:
Warm Up
Find the tangential speed of unknown
planet with a mass 2x1022kg revolving
around a 3x1032 kg star at a radius
(center to center) of 4x1013m.
f3A describing forces with velocity, acceleration, etc.
I –Independent Resilient Individuals
RST.11-12.9 Synthesize information from a range of
sources into coherent understanding of a process,
phenomenon, or concept,…
Learning Goal: SWBAT compare their
work and power capabilities with that of
a horse and light bulb
Agenda:
1. Warm Up
2. Collect HW
3. Collect AP Practice Test
4. Review CAP 7-9, Collect CAP 4-8
5. Lab: The Watt and the Horsepower. (Do
Individually, not in groups)
Homework
CAP #10
AP PHYSICS
THURSDAY 15.01.22
STANDARDS:
f3A describing forces with velocity, acceleration, etc.
Warm Up
Find the tangential speed of unknown
asteroid with a mass of 1.2x108 kg
revolving around a 4.3x1029 kg star
with a radius (center to center) of
2x1014m.
I –Independent Resilient Individuals
RST.11-12.9 Synthesize information from a range of
sources into coherent understanding of a process,
phenomenon, or concept,…
Learning Goal: SWBAT compare their
work and power capabilities with that of
a horse and light bulb
Agenda:
1. Warm Up
2. Review EAP#1 Stamp HW
3. The Watt and Horsepower Lab #3
Homework
EAP#1
AP PHYSICS
FRIDAY 15.01.23
STANDARDS:
Warm Up
A 20 N force directed 30 degrees
above the horizontal pushes a box.
It is displaced 2 m before it stops.
Find the total work done.
f3A describing forces with velocity, acceleration, etc.
I –Independent Resilient Individuals
RST.11-12.9 Synthesize information from a range of
sources into coherent understanding of a process,
phenomenon, or concept,…
Learning Goal: SWBAT describe the
transfer of energy due to friction
mathematically and discuss their results.
Agenda:
1. Warm Up
2. Review EAP #1
3. Work and the Force Friction #4
Homework
EAP#2
#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,
CAP #7
1. Deimos, a satellite of Mars, has an average radius of 6.3 km. If the gravitational
force between Deimos and a 3.0 kg rock at its surface is 2.5x10-2N, what is the
Mass of Deimos?
2. In 1874, a swarm of locusts descended on Nebraska. The swarm’s mass was
estimated to be 25x109kg. If this swarm were split in half and the halves
separated by 1.0x103 km, what would the magnitude of the gravitational force
between the halves be?
3. Jupiter, the largest planet in the solar, system, has a mass 318 times that of Earth
and a volume (4/3πr3) that is 1323 times greater than the Earth’s. Calculate the
magnitude of the gravitational force exerted on a 50.0 kg mass on Jupiter’s
surface. (look up the mass and radius of the earth online or in your books)
CAP#8 GRAVITATION FRQ
A student is given the set of orbital data for some of the moons of Saturn shown
below and is asked to use the data to determine the mass MS of Saturn. Assume
the orbits of these moons are circular.
a. Write an algebraic expression for the gravitational force between Saturn and one of
its moons.
b. Use your expression from part (a) and the assumption of circular orbits to derive an
equation for the orbital period T of a moon as a function of its orbital radius R.
c. Which quantities should be graphed to yield a straight line whose slope could be
used to determine Saturn’s mass?
d. Complete the data table by calculating the two quantities to be graphed. Label the
top of each column, including units.
e. Plot the graph on the axes below. Label the axes with the variables used and
appropriate numbers to indicate the scale.
f. Using the graph, calculate a value for the mass of Saturn.
CAP#9
To study circular motion, two students use the hand-held device shown above, which
consists of a rod on which a spring scale is attached. A polished glass tube attached at
the top serves as a guide for a light cord attached the spring scale. A ball of mass
0.200 kg is attached to the other end of the cord. One student swings the teal around
at constant speed in a horizontal circle with a radius of 0.500 m. Assume friction and
air resistance are negligible.
a. Explain how the students, by using a timer and the information given above, can
determine the speed of the ball as it is revolving.
b. The speed of the ball is determined to be 3.7 m/s. Assuming that the cord is horizontal
as it swings, calculate the expected tension in the cord.
c. The actual tension in the cord as measured by the spring scale is 5.8 N. What is the
percent difference between this measured value of the tension and the value
calculated in part b.?
The students find that, despite their best efforts, they cannot swing the ball so that the cord
remains exactly horizontal.
d. i. On the picture of the ball below, draw vectors to represent the forces acting on the ball
and identify the force that each vector represents.
ii. Explain why it is not possible for the ball to swing so that the cord remains exactly
horizontal.
iii. Calculate the angle that the cord makes with the horizontal.
EAP #1 WORK & POWER
1. Lake Point Tower in Chicago is the tallest apartment building in the United States.
Suppose you take the elevator from the street level to the roof of the building. The
elevator moves almost the entire distance at constant speed, so that it does 1.15x105J
of work on you as it lifts the entire distance. If you mass is 60.0 kg, how tall is the
building? If it takes 2 minutes, how much power does the elevator use.
2. During World War II, 16 huge wooden hangers were built for the United States Navy
airships. The hangers were over 300 m long and had a maximum height of 52.0 m.
Imagine a 40 kg block being lifted by a winch from the ground to the top of the
hangar’s ceiling. If the winch does 2.08x104J of work in lifting the block, what force is
exerted on the block? How much power is used by the winch if it takes 30 seconds ?
3. The longest shish kebab ever made was 881.0 m long. Suppose the meat and
vegetables need to be delivered in a cart from one end of this shish kebab’s skewere to
the other end. A cook pulls the cart by applying a force of 40.0 N at an angle of 45.00
degrees above the horizontal. If the force of friction acting on the cart is 28.00 N, what
is the net work done on the cart and its contents during the delivery?
EAP #2 TRANSFER OF ENERGY
A. From your Lab #3: Graph Force (y axis) vs. displacement (x axis). Create a best fit
line. Answer: How would you use the graph to find Work or (ΔK) the change in kinetic
energy? From your graph, find the change in kinetic energy.
1. The tops of the towers of the Golden Gate Bridge, in San Francisco, are 227 m above
the water. Suppose a worker drops a 655 g wrench from the top of a tower. If the
average force of air resistance is 2.20 percent of the force of free fall, what will the
kinetic energy of the wrench be when it hits the water?
2. Bonny Blair of the United States set a world record in speed skating when she skated
5.00x102 m with an average speed of 12.92 m/s. Suppose Blair crossed the finish
line at this speed and then skated to a stop. If the work done by friction over a certain
distance was -2830 J, what would Blair’s kinetic energy be, assuming her mass to be
55.0 kg.
3. The summit of Mount Everest is 8848.0 m above sea level, making it the highest
summit on Earth. In 1953, Edmund Hillary was the first person to reach the summit.
Suppose upon reaching there, Hillary slid a rock with a 45.0 g mass down the side of
the mountain. If the rock’s speed is 27.0 m/s when it is 8806.0 m above sea level,
how much work was done on the rock by air resistance?
4. In 1990, Roger Hickey of California reached a speed 35.0 m/s on his skateboard.
Suppose it took 21 kJ of work for Roger to reach this speed from a speed of 25.0 m/s.
Calculate Hickey’s mass.