Second SemesterFinal Exam Review

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

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 ProblemsAstronauts in an orbiting space shuttle experience a sensation of weightlessness because .

a. the space shuttle is not affected by the earth’s gravityb. the space shuttle is moving away from the earthc. the space shuttle is falling freely toward the earthd. the mass of the space shuttle decreases as the distance from the earth increases

Gravity ProblemsAstronauts in an orbiting space shuttle experience a sensation of weightlessness because .

a. the space shuttle is not affected by the earth’s gravityb. the space shuttle is moving away from the earthc. the space shuttle is falling freely

toward the earthd. 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 Nq

FE

Electrostatic Problems

• You are outside during an electrical storm. Where is the safest place to hide?

a)Standing in a field with your umbrellab)Under a treec) Standing in field without your umbrellad)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 umbrellab)Under a treec) Standing in field without your umbrellad)In a metal mesh chicken coop.

Electricity Problems

• You add resistors in parallel to a circuit. What happens to the overall resistance?

a)It increasesb)It decreasesc) It stays the samed)Too little information to tell

Electricity Problems

• You add resistors in parallel to a circuit. What happens to the overall resistance?

a)It increasesb)It decreasesc) It stays the samed)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 Prepared•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?

•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 Prepared•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?

•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 Prepared•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?

•A sound wave is produced at room temperature. If the frequency of the wave is 153 Hz…a)Find the distance between compressionsb)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 Prepared•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?

•A sound wave is produced at room temperature. If the frequency of the wave is 153 Hz…a)Find the distance between compressionsAnswer = 2.24 ma)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 mediumc)Is this a mechanical wave?Answer = Yes! All sound waves are mechanical.

Basic Prepared•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.

•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 Prepared•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.

•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 harmonicc)Describe how nodes and antinodes are created. Answer = interference of identical waves moving in opposite directions

Basic Prepared•What unit do we commonly use to measure sound intensity?

•Someone whispers to you at 30 dB. You answer back at 70 dB. How much louder were you being?

Basic Prepared•What unit do we commonly use to measure sound intensity? dB

•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 PreparedYou take a yellow rose

under a blue light. What color will the rose appear to be?

A) yellowB) RedC) GreenD) Black

• 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

Basic PreparedYou take a yellow rose

under a blue light. What color will the rose appear to be?

A) YellowB) RedC) GreenD) BlackAnswer = Black—a yellow

rose can only reflect green and/or red, not blue

• 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

• 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

Principle of Optical refraction

Basic PreparedA 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?

Draw a light wave. Label its parts and describe its properties.

How far can light travel in 50 seconds?

Basic PreparedA radio wave is

traveling through a city.

• How far will it travel it travel in 2.0 minutes?

Answer = 3.6 x 1010 m

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

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 moved)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 moved)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 forceb) Changing the weight of the objectc) Changing the area of contact without

changing the mass of the dragged objectd) 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 forceb)Changing the weight of the objectc) Changing the area of contact without

changing the mass of the dragged objectd) 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 staircaseb)Taking the front spiral staircase.c) Climbing a specially built rampd)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 staircaseb)Taking the front spiral staircase.c) Climbing a specially built rampd)All of these would take the same amount of

work.