Download Finals Review 2nd Sem2012

Second Semester
Final Exam Review
Forces
Mean Mrs.Trunchbull whirls a girl (weight
325 N) by the pigtails. If the girl is going
around with a velocity of 15 m/s and the
radius of the circle is 1.05 m,
a. What is her centripetal acceleration?
b. What force is required to keep her
whirling around like this?
Forces
Mean Mrs.Trunchbull whirls a girl (weight 325 N)
by the pigtails. If the girl is going around with a
velocity of 15.0 m/s and the radius of the circle is
1.05 m,
a. What is her centripetal acceleration?
ac = v2/r = (15.0m/s)2/1.05m = 214 m/s2
b. What force is required to keep her whirling
around like this?
Fc = mac = (325N/9.80) x 214 = 7097 N =
7.10 x 103 N
Forces
Herman pushes on the handle of a lawn mower
with a force of 325 N at an angle of 32 degrees
down. The lawn mower has a mass of 12 kg.
The force of friction between the lawnmower
and the ground is 222N. What will be the
acceleration of the lawnmower?
Forces
Herman pushes on the handle of a lawn mower
with a force of 325 N at an angle of 32 degrees
down. The lawn mower has a mass of 12 kg.
The force of friction between the lawnmower
and the ground is 222N. What will be the
acceleration of the lawnmower?
4.5 m/s2
Energy Problems
You throw an apple at a target. If the apple has a
mass of 1.5 kg and you throw it with a velocity
of 3.0 m/s. How much kinetic energy does the
apple have?
Energy Problems
You throw an apple at a target. If the apple has a
mass of 1.5 kg and you throw it with a
velocity of 3.0 m/s. How much kinetic energy
does the apple have?
6.75 J
Energy Problems
You throw the apple up in the air. It goes up
from your hand (h=1.0 m) and reaches a
height of 5.0 m. How much energy does this
take? Remember, the apple has a mass of 1.5
kg.
Energy Problems
You throw the apple up in the air. It goes up
from your hand (h=1.0 m) and reaches a
height of 5.0 m. How much energy does this
take? Remember the apple has a mass of 1.5
kg.
59 J
Gravity Problems
Astronauts in an orbiting space shuttle
experience a sensation of weightlessness
because
.
a. the space shuttle is not affected by the
earth’s gravity
b. the space shuttle is moving away from
the earth
c. the space shuttle is falling freely
toward the earth
d. the mass of the space shuttle
decreases as the distance from the earth
increases
Gravity Problems
Astronauts in an orbiting space shuttle
experience a sensation of weightlessness
because
.
a. the space shuttle is not affected by the
earth’s gravity
b. the space shuttle is moving away from
the earth
c. the space shuttle is falling freely
toward the earth
d. the mass of the space shuttle
decreases as the distance from the earth
increases
Gravity Problems
Two satellites of equal mass are put into orbit 31
m apart. The gravitational force between
them is 2.0 x 10-7 N. What is the mass of
each satellite?
Gravity Problems
Two satellites of equal mass are put into orbit 31
m apart. The gravitational force between
them is 2.0 x 10-7 N. What is the mass of
each satellite?
m= 1697 kg = 1700 kg (two sig figs)
Electrostatics Problems
You want to charge a ball using induction. You
would:
a)Rub the ball with silk, removing electrons and
charging it
b)Rub the ball with silk, removing protons and
charging it
c) Bring a charged object near it, causing the
electrons to move.
Electrostatics Problems
4. You want to charge a ball using induction. You
would:
a)Rub the ball with silk, removing electrons and
charging it
b)Rub the ball with silk, removing protons and
charging it
c) Bring a charged object near it, causing the
electrons to move.
Electrostatic Problems
• A balloon with a charge of 7.6 x 10-6 C is
sitting in an electric field with a strength of 4.5
x 10-5 N/C. How much force does the object
feel?
Electrostatic Problems
• A balloon with a charge of 7.6 x 10-6 C is
sitting in an electric field with a strength of 4.5
x 10-5 N/C. How much force does the object
feel?
3.4 x 10-10 N
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Electrostatic Problems
• You are outside during an electrical storm.
Where is the safest place to hide?
a)Standing in a field with your umbrella
b)Under a tree
c) Standing in field without your umbrella
d)In a metal mesh chicken coop.
Electrostatic Problems
• You are outside during an electrical storm.
Where is the safest place to hide?
a)Standing in a field with your umbrella
b)Under a tree
c) Standing in field without your umbrella
d)In a metal mesh chicken coop.
Electricity Problems
• You add resistors in parallel to a circuit. What
happens to the overall resistance?
a)It increases
b)It decreases
c) It stays the same
d)Too little information to tell
Electricity Problems
• You add resistors in parallel to a circuit. What
happens to the overall resistance?
a)It increases
b)It decreases
c) It stays the same
d)Too little information to tell
Electricity Problems
• You hook a 5.0 ohm resistor and 6.0 ohm
resistor up in series to a 12 V battery. What is
the current in this circuit?
Electricity Problems
• You hook a 5.0 ohm resistor and 6.0 ohm
resistor up in series to a 12 V battery. What is
the current in this circuit?
1.1 A
Electricity Problems
• You hook a 5.0 ohm resistor and 6.0 ohm
resistor up in parallel to a 12 V battery. What
is the total current in this circuit?
Electricity Problems
• You hook a 5.0 ohm resister and 6.0 ohm
resister up in parallel to a 12 V battery. What
is the total current in this circuit?
4.4 A
Basic
•What is the period of
a wave?
•What units are used
to describe the period?
•What is the symbol for
the period?
•What is a wavelength?
•What units are used
to describe the
wavelength?
•What is the symbol for
the wavelength?
Prepared
•A slinky will transmit a
wave at a speed of
7.34 m/s. The distance
from a crest to a
trough in this wave is
0.31 m. What is the
period of this wave?
Basic
•What is the period of
a wave?
•What units are used
to describe the period?
•What is the symbol for
the period?
•What is a wavelength?
•What units are used
to describe the
wavelength?
•What is the symbol for
the wavelength?
Prepared
•A slinky will transmit a
wave at a speed of
7.34 m/s. The distance
from a crest to a
trough in this wave is
0.31 m. What is the
period of this wave?
Answer = 0.084 s
Basic
•You have a lovely
singing voice.
a)What type of wave is
this? Draw it.
b)Label the important
parts of the wave.
c)How many waves are
made every second?
d)Is this a mechanical
wave?
Prepared
•A sound wave is produced
at room temperature. If the
frequency of the wave is
153 Hz…
a)Find the distance
between compressions
b)Draw the wave and label
the important parts of the
wave.
c)What is responsible for
the speed of a wave?
d)Is this a mechanical
wave?
Basic
•You have a lovely
singing voice.
a)What type of wave is
this? Draw it.
b)Label the important
parts of the wave.
c)How many waves are
made every second?
d)Is this a mechanical
wave?
Prepared
•A sound wave is produced at
room temperature. If the
frequency of the wave is 153
Hz…
a)Find the distance between
compressions
Answer = 2.24 m
a)Draw the wave and label the
important parts of the wave.
b)What is responsible for the
speed of a wave? Answer = the
density and elasticity of the
medium
c)Is this a mechanical wave?
Answer = Yes! All sound waves
are mechanical.
Basic
•What is a transverse
wave? Give an
example.
•What is a longitudinal
wave? Give and
example.
•What is a standing
wave?
•Draw a complete
standing wave and
label its wavelength,
nodes and antinodes.
Prepared
•A 12 meter rope is
used to create a
standing wave with a
wavelength of 3 m.
a)Draw the standing
wave.
b)What harmonic
frequency produced
this wave form?
c)Describe how nodes
and antinodes are
created.
Basic
•What is a transverse
wave? Give an
example.
•What is a longitudinal
wave? Give and
example.
•What is a standing
wave?
•Draw a complete
standing wave and
label its wavelength,
nodes and antinodes.
Prepared
•A 12 meter rope is used to
create a standing wave with
a wavelength of 3 m.
a)Draw the standing wave.
b)What harmonic frequency
produced this wave form?
Answer = eighth harmonic
c)Describe how nodes and
antinodes are created.
Answer = interference of
identical waves moving in
opposite directions
Basic
•What unit do we
commonly use to
measure sound
intensity?
Prepared
•Someone whispers to
you at 30 dB. You
answer back at 70 dB.
How much louder were
you being?
Basic
•What unit do we
commonly use to
measure sound
intensity? dB
Prepared
•Someone whispers to
you at 30 dB. You
answer back at 70 dB.
How much louder were
you being? Answer =
you were speaking
with 10000 times more
sound intensity
(10x10x10x10); each
10 dB jump = 10x
Basic
• You take a yellow
rose under a red
light. What color
will the rose
appear to be?
•
•
•
•
A) yellow
B) Red
C) Green
D) Black
Prepared
You take a yellow rose
under a blue light.
What color will the
rose appear to be?
A) yellow
B) Red
C) Green
D) Black
Basic
• You take a yellow
rose under a red
light. What color
will the rose
appear to be?
•
•
•
•
A) yellow
B) Red
C) Green
D) Black
Prepared
You take a yellow rose
under a blue light. What
color will the rose appear
to be?
A) Yellow
B) Red
C) Green
D) Black
Answer = Black—a yellow
rose can only reflect
green and/or red, not
blue
Principle of Optical refraction
• Snell’s Law: describes the angle of refracted
light.
• ni,r = index of refraction (see table 17-1; p.397)
• ni sin
Θi = nr sin Θr
• If ni < nr ; then goes into a more optically dense
medium and bends towards the normal line.
• If ni > nr ; then bends away from the normal
Basic
Draw a light wave.
Label its parts and
describe its
properties.
How far can light travel
in 50 seconds?
Prepared
A radio wave is
traveling through a
city. It has a
wavelength of 45 m.
• What is the
frequency of this
wave?
• How far will it travel
it travel in 2
minutes?
Basic
Draw a light wave.
Label its parts and
describe its
properties.
How far can light travel
in 50.0 seconds?
Answer =
1.50 x 1010 m
Prepared
A radio wave is
traveling through a
city.
• How far will it travel
it travel in 2.0
minutes?
Answer = 3.6 x 1010 m
Question 1
• How much power does an elevator exert
lifting a 3423 kg elevator 10.0 meters in 12.0
seconds?
Question 1
• How much power does an elevator exert
lifting a 3423 kg elevator 10.0 meters in 12.0
seconds?
mgh / t = P
(3423 * 9.80 * 10.0) / 12.0 = 27954.5 W =
2.80x104 W
Question 2
• Two astronauts floating in space together
double the distance between them. What
happens to the gravitation force between
them?
Question 2
• Two astronauts floating in space together
double the distance between them. What
happens to the gravitation force between
them?
• It decreases to ¼ of what it was.
Question 3
I rub a balloon against my head. How am I charging
up the balloon.
a) Charging by friction, causing the electrons to
move
b) Charging by induction, causing the protons to
move
c) Charging by friction, causing the protons to
move
d) Charging by induction, causing the electrons to
move
Question 3
I rub a balloon against my head. How am I charging
up the balloon.
a)Charging by friction, causing the electrons to
move
b)Charging by induction, causing the protons to
move
c) Charging by friction, causing the protons to move
d)Charging by induction, causing the electrons to
move
Question 4
True or false: Friction is necessary for you to
drive your car.
Question 4
True or false: Friction is necessary for you to
drive your car. Explain your answer.
True! Without friction, we could not start or
stop.
Question 7
As a roller coaster rides down a track, for a split
second it has a kinetic energy of 1023 J and a
potential energy of 786 J. What is the
mechanical energy of the cart at this
moment?
Question 7
As a roller coaster rides down a track, for a split
second it has a kinetic energy of 1023 J and a
potential energy of 786 J. What is the
mechanical energy of the cart at this
moment?
786 + 1023 = 1809 J
Question 8
What do the arrows in an electric field tell us?
Question 8
What do the arrows in an electric field tell us?
The direction a small positive test charge would
move.
Question 9
Which of the following would not change the
frictional force of an object you are dragging.
a) Changing the angle or your pulling force
b) Changing the weight of the object
c) Changing the area of contact without
changing the mass of the dragged object
d) Changing what the surfaces in contact are
made of.
Question 9
Which of the following would not change the
frictional force of an object you are dragging.
a)Changing the angle or your pulling force
b)Changing the weight of the object
c) Changing the area of contact without
changing the mass of the dragged object
d) Changing what the surfaces in contact are
made of.
Question 12
You are moving into your new dorm and carrying
your bag up to your room. What would take
less work from a physics perspective.
a)Taking the steep back staircase
b)Taking the front spiral staircase.
c) Climbing a specially built ramp
d)All of these would take the same amount of
work.
Question 12
You are moving into your new dorm and carrying
your bag up to your room. What would take
less work from a physics perspective.
a) Taking the steep back staircase
b) Taking the front spiral staircase.
c) Climbing a specially built ramp
d) All of these would take the same amount of
work.