apphysicsbexamreview-090425125639-phpapp01

7/28/2019 apphysicsbexamreview-090425125639-phpapp01

1/173

SOHCAHTOA


2/173

Whats the difference between distance anddisplacement?

Distance is the total amount an object hastraveled.

Displacement is the objects change inposition


3/173

A rock is thrown straight upward from theedge of a 30 m cliff, rising 10 m then fallingall the way down to the base of the cliff. Findthe rocks displacement.

An infant crawls 5 m east, then 3 m north,then 1 m. What is the infants DISTANCE andDISPLACEMENT

An athlete runs exactly once around thetrack, a total distance of 500 m. Find therunners displacement for the race


4/173

S = d/t, or V = x/t

If the infant in the previous example takes 20

seconds to complete his journey, find themagnitude of his average velocity.

Is it possible to move with constant speed butnot constant velocity? Is it possible to mov e

with constant velocity but not constantspeed?


5/173

a = v/t

A car is traveling in a straight line along a

highway at a constant speed of 80 miles perhour for 10 seconds. Find its acceleration.

Spotting a police car ahead, a driver of a carslows from 32 m/s to 20 m/s in 2 seconds.

Find the cars average acceleration


6/173

tvvx o 21

2

21 attvx o

atvv o

axvv o 222


7/173

An object with an initial velocity of 4 m/s movesalong a straight axis under constant acceleration.Three seconds later, its velocity is 14 m/s. Howfar did it travel during this time? 27m

A car thats initially traveling at 10 m/saccelerates uniformly for 4 seconds at a rate of 2m/s2 in a straight line. How far does the cartravel during this time? 56m

A rock is dropped off a cliff thats 80 m high. Ifit strikes the ground with an impact velocity of40 m/s, what acceleration did it experienceduring its descent? 10 m/s2


8/173


9/173


10/173

The area under a velocity vs. time graphequals the displacement.


11/173

Page 23-24


12/173

Gravity is 10 m/s2

y = at2


13/173

A rock is dropped from an 80 m cliff. How longdoes it take to reach the ground? 4s

A baseball is thrown straight upward with aninitial speed of 20 m/s. How high will it go? 20m

One second after being thrown straight down, anobject is falling with a speed of 20 m/s. Howfast will it be falling 2 seconds later? -40 m/s

If an object is thrown straight upward with an

initial speed of 8 m/s and takes 3 seconds tostrike the ground, from what height was theobject thrown? 21m


14/173

X-motion is INDEPENDENT of Y-motion

An object is thrown horizontally with an initialspeed of 10 m/s. It hits the ground 4 secondslater. How far did it drop in 4 seconds? -80m

From a height of 100 m, a ball is thrownhorizontally with an initial speed of 15 m/s. Howfar does it travel horizontally in the first 2seconds? 30m

A rolling ball falls off a lab desk with a velocity of2 m/s. The height of the lab desk is 1 m. Howfar away does the ball land?


15/173


16/173

Any push or pull is called a force (N)

- Tension

- Gravitational force- Air resistance

- Normal force

- Frictional force

- Electrostatic force- Nuclear forces


17/173

Law of Inertia A body at rest wants to stayat rest or a body in motion wants to stay inmotion unless acted upon by an outside force


18/173

F = ma Force is measure in Newtons (kgm/s2)


19/173

For every action, there is an equal butopposite reaction


20/173

What net force is required to maintain a 5000 kgobject moving at a constant velocity ofmagnitude 7500 m/s?

How much force is required to cause an object of

mass 2 kg to have an acceleration of 4 m/s2? 8 N An object feels two forces; one of strength 8 N

pulling to the left and one of strength 20 Npulling to the right. If the objects mass is 4 kg,what is its acceleration? 3 m/s2

A book whose mass is 2 kg rests on a table. Findthe magnitude of the force exerted by the tableon the book. 20 N


21/173


22/173

A can of paint with a mass of 6 kg hangsfrom a rope. If the can is to be pulled up to arooftop with a constant velocity of 1 m/s,what must the tension in the rope be? 60 N

What force must be exerted to lift a 50 Nobject with an acceleration of 10 m/s2? 100 N


23/173

The force that is perpendicular to the surface

A book whose mass is 2 kg rests on a table.Find the magnitude of the normal forceexerted by the table on the book. 20 N


24/173

Parallel to the surface and opposite thedirection of the intended motion

1) Static friction the force that resistsmovement

Fs = sFN2) Kinetic friction the force that acts on a

moving objectFk = kFN


25/173

A crate of mass 20 kg is sliding across awooden floor. The coefficient of kineticfriction between the crate and the floor is 0.3 Determine the strength of the friction force acting

on the crate. 60 N If the crate is being pulled by a force of 90 N

(parallel to the floor), find the acceleration of thecrate. 1.5 m/s2


26/173


27/173

A block slides down a frictionless, inclinedplane that makes a 30 degree angle with thehorizontal. Find the acceleration of thisblock. 5 m/s2

Suppose the same block slides down thesame inclined plane with a coefficient ofkinetic friction of 0.3. Find the accelerationof the block


28/173


29/173

Ac = v2/r Fc = mv

2/r Anything pointing towards the center of the circle

is positive, anything pointing away is negative

An object of mass 5 kg moves at a constantspeed of 6 m/s in a circular path of radius 2 m.Find the objects acceleration and the net forceresponsible for its motion. 18 m/s2 ; 90 N

An athlete who weighs 800 N is running around acurve at a speed of 5.0 m/s with a radius of 5.0m. Find the centripetal force acting on him &what provides the centripetal force? 400 N &static friction


30/173

A roller-coaster car enters the circular loopportion of the ride. At the very top of thecircle, the speed of the car is 15 m/s, and theacceleration points straight down. If thediameter of the loop is 40 m and the totalmass of the car is 1200 kg, find themagnitude of the normal force exerted by the

track on the car at this point. 1500 N How would the normal force change if the car

was at the bottom of the circle? 25,500 N


31/173

= FrsinCounterclockwise Torque is positiveClockwise Torque is negative


32/173

What is the net torque in the followingpicture? 5.6 Nm


33/173


34/173

W = Fdcos

A crate is moved along a horizontal floor by aworker whos pulling on it with a rope thatmakes a 30 degree angle with the horizontal.The tension in the rope is 69 N and the crateslides a distance of 10 m. How much work isdone on the crate by the worker? 600 J


35/173

A box slides down an inclined plane with anangle of 37 degrees. The mass of the blockis 35 kg, the coefficient of kinetic friction is0.3, and the length of the ramp is 8 m.

1. How much work is done by gravity? 1690 J

2. How much work is done by the normal force?

0 N3. How much work is done by friction? -671 J

4. What is the total work done?


36/173


37/173


38/173

KE = mv2

The energy an object possesses due to itsmotion

A pool cue striking a stationary billiard ball(m = 0.25 kg) gives the ball a speed of 2 m/s.If the average force of the cue on the ball was200 N, over what distance does this force act?

0.0025 m


39/173

PE = mgh The energy an object possesses due to its

position

A 60 kg stuntwoman scales a 40 m tall rock.What is her gravitational potential energy? Ifshe were to jump off the cliff, what would her

final velocity be? 24,000 J; 28 m/s


40/173

Ei = Ef KEi + PEi = KEf+ Pef

A ball of mass 2 kg is gently pushed off the edge

of a table that is 5 m above the floor. Find thespeed of the ball as it strikes the floor. 10 m/s

A box is projected up a long ramp with an inclineof 37 degrees with an initial speed of 10 m/s. If

the surface of the ramp is frictionless, how highup the ramp will the box go? What distancealong the ramp will it slide?


41/173

A skydiver jumps from a hovering helicopterthats 3000 m above the ground. If airresistance can be ignored, how fast will he befalling when his altitude is 2000 m? 140 m/s

Wile E. Coyote (m = 40 kg) falls off a 50 mhigh cliff. On the way down, the force of airresistance has an average strength of 100 N.

Find the speed with which he crashes into theground. 27 m/s


42/173

The rate at which work is done P = W/t or P = Fv

A mover pushes a large crate (m = 75 kg)from the inside of the truck to the back end(distance of 6 m), exerting a steady push of300 N. If he moves the crate this distance in20 s, what is his power output? 90 W

What must be the power output of an elevatormotor that can lift a total mass of 1000 kgand give the elevator a constant speed of 8.0m/s? 80,000 W or 80 kW


43/173


44/173

p = mv F = p/t = mv/t Momentum is also conserved

A golfer strikes a golf ball of mass 0.05 kgand the time of impact between the golf cluband the ball is 1 ms. If the ball acquires a

velocity of magnitude 70 m/s, calculate theaverage force on the ball. 3500 N


45/173

J = Ft

An 80 kg stuntman jumps out of a window thats45 m above the ground.

1. How fast is he falling when he reaches theground? 30 m/s2. He lands on an air bag, coming to rest in 1.5s.

What average force does he feel while coming torest? -1600 N

3. What if he had instead landed on the ground(impact time 10 ms)? -240,000 N


46/173


47/173

Elastic Collisions Kinetic Energy is conserved Inelastic Collisions Kinetic Energy is not

conserved.

Two balls roll toward each other. The red ballhas a mass of 0.5 kg and a speed of 4 m/s justbefore impact. The green ball has a mass of 0.2kg and a speed of 2 m/s. After the head-oncollision, the red ball continues forward with a

speed of 2 m/s. Find the speed of the green ballafter the collision. Was the collision elastic? 3.0m/s; no


48/173


49/173


50/173

F = Gm1m2 / r2G = 6.67 x 10-11 N m2 / kg2

Given that the radius of the earth is 6.37 x106m, determine the mass of the earth. 6.1 x1024 kg

An artificial satellite of mass m travels at a

constant speed in a circular orbit of radius Raround the earth (mass M). What is the speedof the satellite? GM/R


51/173

F = -kx The stiffer the spring, the greater the k

Force and acceleration are greatest whendisplacement is greatest.

A 12 cm long spring has a spring constant of400 N/m. How much force is required to

stretch the spring to a length of 14 cm? 8 N


52/173

PEelastic = kx2 PE is maximized when spring is at the

endpoints, KE is minimum

PE is 0 when spring is passing through x=0(equilibrium) and KE is maximum


53/173

A 0.05 kg block oscillates on a spring whoseforce (spring) constant is 500 N/m. Theamplitude of the oscillations is 4.0 cm.Calculate the maximum speed of the block. 4

m/s A 2.0 kg block is attached to an ideal spring

with a force constant of 500 N/m. Theamplitude is 8.0 cm. Determine the total

energy of the oscillator and the speed of theblock when its 4.0 cm from equilibrium. 1.6J; 1.1 m/s


54/173

f = 1/T

T = 1/f

T = 2m/k w = 2f, 2/T, k/m

A block oscillating on the end of a spring movesfrom is position of maximum stretch tomaximum compression in 0.25 s. Determine theperiod and frequency. 0.5 s; 2 Hz

A student observing an oscillating block counts

45.5 cycles in one minute. Determine itsfrequency and period. .758 Hz; 1.32s


55/173

A 2.0 kg block is attached to a spring whose

spring constant is 300 N/m. Calculate thefrequency and period. 1.9 Hz; 0.51 s

A block is attached to a spring and set intooscillatory motion and its frequency is

measured. If this block were removed andreplaced by a second block with the massof the first block, how would the frequency ofthe oscillations compare? f increases by a

factor of 2


56/173

KE is maximum at the equilibrium position

Frequency nor period depends on theamplitude for any object in SHM

Lg

T 2


57/173

A simple pendulum has a period of 1s onEarth. What would its period be on the moon,where g is 1/6thof the earths value?2.4s


58/173


59/173

In the drawing, one cyc leis shaded in color.The ampl i tudeA is the maximum excursion of a particle of the medium fromthe particles undisturbed position.

The wavelengthis the horizontal length of one cycle of the wave.

The per iodis the time required for one complete cycle.

The f requencyis related to the period and has units of Hz, or s-1.

Tf

1


60/173

The period of a traveling wave is 0.5s, itsamplitude is 10 cm, and its wavelength is 0.4m. What are its frequency and wave speed?2Hz; 0.8 m/s

fT

v


61/173

Lm

Fv


62/173

When 2 or more waves meet, they overlap(interfere)

2 Types of interference Constructive Interference (added together)

Destructive Interference (subtracted from eachother)

2 waves, one with amplitude of 8 cm and the

other with an amplitude of 3 cm travel in thesame direction on a string and overlap. Whatare the maximum and minimum amplitudes?11cm; 5 cm


63/173


64/173


65/173

L = n(1/2) f = nV/2L

A string of length 12 m thats fixed at bothends supports a standing wave with a total of5 nods. What are the harmonic number andwavelength of this standing wave?


66/173

LONGITUDINAL SOUND WAVES

The area of condensation is

the region of compression

with increased air pressure

The area of rarefaction is

the region behind the

condensation withdecreased air pressure


67/173

Sound travels fastest in solids, then liquids,then gases

adBv


68/173

The change in frequency and wavelength thatoccurs when the source and detector are inrelative motion. Relative motion toward each other results in a

frequency shift upward, and relative motion awayfrom each other results in a frequency shiftdownward


69/173


70/173

p = m/v specific gravity = psubstance / pwater (1000

kg/m3)

A cork has a volume of 4 cm3 and weighs .01N. What is the specific gravity of the rock?0.25


71/173

P = F/A 1 atm = 101,300 Pa (1.013 x 105 Pa)

A vertical column made of cement has a basearea of 0.5 m2. If the height is 2 m, and thesp. Gravity of cement is 3, how muchpressure does this column exert on theground? 6 x 104 Pa


72/173

Fg = pvg Pliquid = pgh (depends only on density and

depth)

Ptotal = Patm + Pliquid

What is the gauge pressure of a swimmingpool at a point 1 m below the surface? 1 x104Pa


73/173

What happens to the gauge pressure if wedouble the depth below the surface of aliquid? What happens to the total pressure?Gauge pressure increases by a factor of 2;

Total pressure increases by less than a factorof 2

A flat piece of wood of area 0.5 m2 is lying atthe bottom of a lake. If the depth of the lake

is 30 m, what is the force on the wood due tothe pressure? 2 x 105 N


74/173

The net upward force of an object in a liquidis called the buoyant force.

Archimedes Principle - The strength of thebuoyant force is equal to the weight of the

fluid displaced by the object.FB = pvg

Vsub = pobject

Vtotal pfluid


75/173

If pobject < pfluid , then the object will float

A brick with a specific gravity of 2 andvolume of 1.5 x 10-3 m3, is dropped into a

swimming pool full of water. Explain why thebrick will sink. When the brick is lying on thebottom of the pool, what is the magnitude ofthe normal force on the brick? Specific gravity

is greater than 1; 15 N


76/173

A glass sphere of specific gravity 2.5 andvolume of 10-3 m3 is completely submergedin a large container of water. What is theapparent weight of the sphere while

immersed? 15 N


77/173

f = Av A1v1 = A2v2 (flow speed increases when the

pipe narrows or inversely proportional)

A pipe carries water. At one point in the pipe,the radius is 2 cm and the flow speed is 6 m/s.What is the flow rate? What is the flow speedwhere the pipes radius changes to 1 cm? 7.5 x10-3 m3/s; 24 m/s

If the diameter of the pipe increases from 4 cmto 12 cm, what will happen to the flow speed?1/9 the flowrate


78/173

States that energy is conserved for fluid flowP1 + pgy1 + pv1

2 = P2 + pgy2 + pv2


79/173

The pressure is lower where the flow speed isgreater (airplanes, hurricanes).


80/173


81/173

Celsius to Fahrenheit9/5C + 32 = F

Fahrenheit to Celsius

(F-32)5/9 = C

Celsius to Kelvin

C + 273 = K


82/173

Q = mcT (how much heat is added ofremoved

in the system to change the temperature)

Q = mL (changing phases)

Sp. Heat of water = 4186 J/kg C

Rate of heat transfer L

TkA

t

Q


83/173

TLL o

A brass rod 5 m long and 0.01 m indiameter increases in length by 0.05 m whenits temperature is increased by 500C. Asimilar brass rod of length 10 m has a

diameter of 0.02 m. By how much will thisrods diameter increase if its temperature isincreased by 1000C? 4 x 10-4 m


84/173

An aluminum rod (p = 2.7 x 103 kg/m3 has a

radius of 0.01 m and an initial length of 2 m ata temperature of 20C. Heat is added to raiseits temperature to 90C. Its coefficient of linearexpansion is = 25 x 10-6/C, the specific heatis 900 J/kgC, and a thermal conductivity of k =200 J/s mC. What is the mass of the aluminum rod? 1.7 kg What is the amount of heat added to the rod? 107,100J

What is the new length of the rod? 0.0035 m If we were to use this rod to transfer heat between

two objects one side being at 20C and the other sideat 90C, what would the rate of heat transfer be? 2.2

J/s


85/173

P = F/A (Pa)


86/173

Pv = nRT Speed of molecules of a gas

In order for the average speed of themolecules in a given sample of gas to double,

what must happen to the temperature? Sincev is proportional to square root of T, thetemperature must quadruple

m

kT

vrms3

M

RTvrms

3


87/173

A cylindrical container of radius 15 cm andheight 30 cm contains 0.6 mole of gas at 433K. How much force does the confined gasexert on the lid of the container? 35 N


88/173

Zeroth Law Heat flows from the warmerobject to the cooler one until they reachthermal equilibrium.

First Law

W = -PV Work is positive when work is done ON the system

(volume id decreaseing Work is positive when work is done ON the

surroundings (volume is increasing)

WQU


89/173


90/173


91/173


92/173

THE SECOND LAW OF THERMODYNAMICS:

THE LAW OF ENTROPY

Heat flows spontaneously from a substance at ahigher temperature to a substance at a lower

temperature and does not flow spontaneously in the

reverse direction.


93/173

CH QWQ

HH

C

H

C

Q

W

T

T

Q

Qe 11


94/173

A heat engine draws 800 J of heat from its

high temperature source and discards 450 Jof exhaust heat into its cold-temperaturereservoir. How much work does this engineperform and what is its thermal efficiency?

350 J; 44% An inventor proposes a design for a heat

engine that operates between a heat sourceat 500C and a cold reservoir at 25C with an

efficiency of 2/3. Whats your reaction to theinventors claim?


95/173

4 types of thermal processes

An isobaric process is a process that occurs atconstant pressure.

An isochoric process is a process that occurs at

constant volume.

An isothermal process is a process that occurs at

constant temperature.

An adiabatic process is a process during which no

energy is transferred to or from the system as heatat.


96/173


97/173

Consider two small spheres, one carrying acharge of +1.5nC and the other a charge -2.0nC, separated by a distance of 1.5 cm. Findthe electric force between them. -1.2 x 10-4N

2

21

r

qqkF

229 CmN1099.841 ok

2212 mNC1085.8


98/173


99/173

It is the surrounding charges that create the

electric field at a given point.

The electrostatic force points in the direction ofattraction

The electric field always points away from thepositive charge and towards the negative charge.

oq

FE


100/173

Electric field does not depend on the sign of

the test charge

2r

qkE


101/173

A charge q = +3.0 nC is placed at a locationat which the electric field strength is 400N/C. Find the force felt by charge q. 1.2 x10-6 N

A dipole is formed by two point charges, eachof magnitude 4.0 nC, separated by a distanceof 6.0 cm. What is the strength of the electricfield at a point midway between them? 8.0 x

104 N/C


102/173

An object of mass 5g is placed at a distanceof 2 cm above a charged plate. If thestrength of the electric field is 106 N/C, howmuch charge would the object need to have

in order for the electrical repulsion to balancethe gravitational pull? 5 x 10-8 C


103/173

Electric Field Lines Never Cross Always perpendicular to the surface and point

AWAY from the positive TOWARD the negative


104/173

Conductors permit the flow of excess charge;they conduct electricity well (metals) There can be no electrostatic field within the body

of a conductor. Why?

Insulators do not conduct electricity well.Electrons do not flow well A solid sphere of copper is given a negative

charge. Discuss the electric field inside andoutside the sphere.


105/173


106/173

o

AB

o

A

o

B

qW

qq

EPEEPE


107/173

o

AB

o

A

o

B

qW

qq

EPEEPE


108/173


109/173

A positive charge q1 = 2 + 10-6

C is heldstationary, while a negative charge q2 = -1 x10-8 C, is released from rest at a distance of10 cm from q1. Find the kinetic energy

change of charge q2when its 1 cm from q1.0.016 J


110/173

Let Q = 2 x 10-8 C. What is the potential at aPoint P that is 2 cm from Q? 900 V

How much work is done as a charge movesalong an equipotential surface? 0

BAo

ABAB

r

kq

r

kq

q

WVV

rkqV


111/173


112/173

Capacitors are storage devices for electricity.q = CV

Parallel plate capacitors

d

A

Co


113/173

A 10 nF parallel plate capactior holds acharge of 50C on each plate. What is theelectric potential difference between theplates? If the plates are separated by a

distance of 0.2 mm, what is the area of eachplate? 5000 V; 0.23 m2


114/173


115/173

Amount of voltage the battery produces


116/173

I = q/t (Amps, A) The direction of the current is taken to be the

direction that a positive charge would move


117/173

Resistors are devices that control current R = V/I (Ohms Law) Notice that if the current is large, the

resistance is low. If the current is small, the

resistance is high. Resistivity:

A

LR

resistivity in units of ohmmeter


118/173

A wire of radius 1mm and length 2 m is madeof platinum (resistivity = 1 x 10-7m). If avoltage of 9 V is applied between the ends ofthe wire, what will be the resulting current?

140 A


119/173

IVP

RIIRIP 2

R

VV

R

VP

2


120/173

Combining Resistors Series (one after the other):

Add as normal

Parallel (side by side):

Add as inverse

Same voltage applied across each device

321 RRRRS

321

1111

RRRRP


121/173

Calculate the equivalent resistance in the circuit


122/173


123/173

Combining Capacitors Series (one after the other):

Add as inverse

Parallel (side by side):

Add as normal

C = q/V

321 CCCCP

321

1111

CCCCS


124/173


125/173


126/173


127/173

Field lines travel away from the North polesand travel toward the South poles.

X X X X X

X X X X X

X X X X X X X X X X

(into the page) (out of the page)


128/173

The magnetic force always remains

perpendicular to the velocity and is directedtoward the center of the circular path.

sinvqF

Bo


129/173

Right Hand Rule #1 (for positive charges) Thumb Direction particle is traveling Index Direction of Magnetic Field Middle Direction of Magnetic Force

If the charge is NEGATIVE, the force is theopposite direction


130/173


131/173


132/173


133/173

sinILBF


134/173

rIB o2

AmT104 7 o


135/173


136/173

c = 3.00 x 10

8

m/s (speed of light)

f

v


137/173


138/173

Law of Reflection Incident angle is the same as the reflected angle

n = c/v

Snells Law relates the angle of incidenceand the angle of refraction

If n2n1, light bends TOWARD the normal.

2211 sinsin nn


139/173

A beam of light in air is incident upon a pieceof glass striking the surface at an angle of 30degrees. If the index of refraction of theglass is 1.5, what are the angles of reflection

and refraction? 60; 35


140/173

Critical Angle - The angle of incidence atwhich the angle of refraction is 90. No lightis refracted out and the beam is refractedalong the surface.

If the angle of incidence is greater than the criticalangle, no beams of light are refracted.

21

1

2 sin nnn

nc


141/173


142/173

1

2

n

ndd

Apparent d epth,

ob server direct ly

above object

Conceptual Examp le 4On the Inside Looking Out


143/173

A swimmer is under water and looking up at the surface. Someone

holds a coin in the air, directly above the swimmers eyes. To the

swimmer, the coin appears to be at a certain height above thewater. Is the apparent height of the coin greater, less than, or the

same as its actual height?

Light rays are refracted AWAY from the normalwhen going from a higher index of refraction to

a lower index of refraction.

When it is the opposite, the light bends

TOWARD the normal


144/173

Focal length = R/2

Concave Mirrors


145/173

1. An incident ray parallel to the axis that is reflected

through the focal point2. An incident ray that passes through the focalpoint and reflected parallel

3. An incident ray that strikes the vertex is reflectedat an equal angle to the axis

Convex Mirrors1. An incident ray parallel to the axis is reflected

away from the focal point

2. An incident ray directed towards the focal point is

reflected parallel to the axis3. An incident ray that strikes the vertex is reflected

at an equal angle to the axis


146/173


147/173


148/173

Mirror Equation

Magnification Equation

fdd io

111

o

i

o

i

d

d

h

hm

Summary of Sign Con vent ions for Spher ical Mir rors

mirror.concaveaforis f


149/173

mirror.concaveaforis f

mirror.convexaforis f

mirror.theoffrontinisobjecttheifis od

mirror.thebehindisobjecttheifis od

image).(realmirrortheoffrontinisobjecttheifis id

image).(virtualmirrorthebehindisobjecttheifis id

object.uprightanforis m

object.invertedanforis m


150/173

An object of height 4 cm is placed 30 cm infront of a concave mirror whose focal lengthis 10 cm. Wheres the image? 15 cm Is it real or virtual? real

Is it upright or inverted? inverted

What the height? -2cm


151/173

An object of height 4 cm is placed in front ofa convex mirror whose focal length is -30cm. Wheres the image? 12 cm Is it real or virtual? virtual

Is it upright or inverted? upright

Whats the height of the image? 2.4 cm


152/173

Converging lenses cause rays of light toconverge to a focal point.

Diverging lenses cause rays of light todiverge away from the focal point


153/173

Converging Lenses Incident ray parallel to the axis is refracted through

the focal point.

Incident rays pass through the center point of thelens.

Diverging Lenses An incident ray parallel to the axis is reflected away

from the focal point

Incident rays pass through the center point of the

lens.


154/173


155/173

Summary of Sign Convent io ns for Lenses (page 827)

lens.convergingaforis f


156/173

g gf

lens.divergingaforis f

lens.theofleftthetoisobjecttheifis od

lens.theofrightthetoisobjecttheifis od

image).(reallenstheofrightthetoformedimageanforis id

image).(virtuallenstheofleftthetoformedimageanforis id

image.uprightanforis m

image.invertedanforis m


157/173

An object of height 11 cm is placed 44 cm infront of a converging lens with a focal lengthof 24 cm Wheres the image? 53 cm Is it real or virtual? real

Is it upright or inverted? inverted

Whats the height of the image? -13 cm


158/173

An object of height 11 cm is placed 48 cm infront of a diverging lens with a focal length of-24.5 cm. Wheres the image? -16 cm Is it real or virtual? virtual

Is it upright or inverted? upright

Whats the height of the image? 3.7 cm


159/173


160/173

Light behaves like a stream of photons,known as the photoelectric effect.

E = Energy of a photon

h = Plancks Constant 6.63 x 10-34

Js

Increasing the intensity of the incident energymeans bombardment with more photons and

results in the ejection of more photoelectrons = work function

hfE

KEE


161/173

The threshold frequencyis the frequency atwhich photons need to travel to ejectelectrons. f = /h

New unit for photon energy is electronvolt(eV) 1eV = 1.6 x 10-19 J

Examples


162/173

The work function for aluminum is 4.08 ev What is the threshold frequency required to producephotoelectrons from aluminum? 9.86 x 1014 Hz

Classify the electromagnetic radiation that can producephotoelectrons. UV

If light of frequency f = 4.00 x 1015

Hz is used to illuminatea piece of aluminum, What is the KE of ejected photoelectrons? 12.5 eV

Whats the maximum speed of the photoelectron? (Electron mass= 9.11 x 10-31 kg) 2.1 x 106 m/s

If the light described in part b were increased by a factor of2 in intensity, what would happen to the value of theKinetic Energy? Nothing

Bohr theorized that a photon is emitted only


163/173

Bohr theorized that a photon is emitted only

when the electron changes orbits from alarger one with a higher energy to a smallerone with a lower energy

En = Ionization Energy the minimum amount ofenergy that must be supplied to release the atoms

electron Z = number of protons

n = energy level

,3,2,1J1018.22

218 n

n

ZEn

,3,2,1eV6.132

2

nn

ZEn


164/173

How much energy must a ground stateelectron (n=1) in a hydrogen atom absorb tobe excited to the n=4 energy level? 12.8 eV

With the electron in the n=4 level, what

wavelengths are possible for the photonemitted when the electron drops to a lowerenergy level? In what regions of the EMspectrum do these photons lie?


165/173

Light exhibits both wave-like and particle-like characteristics


166/173

h = Plancks Constant p = linear momentum (mv)

ph

atomic mass


167/173

neutronsofNumber

protonsofNumber

neutronsandprotonsofNumber

NZA

atomic

number

atomic mass

number


168/173

How many protons and neutrons arecontained in

29 Protons, 34 Neutrons

uC63

29


169/173

Isotope Contain the same number ofprotons but different number of neutrons

The element Neon (atomic number 10) has

several isotopes. The most abundant isotopecontains 10 neutrons, and two others contain11 and 12. Write symbols for these threenuclides (a nucleus with a specific number of

protons and neutrons


170/173

Example 3The Binding Energy of the Helium Nucleus Revisited

The atomic mass of helium is 4.0026u and the atomic mass of hydrogen


171/173

y g

is 1.0078u. Using atomic mass units, instead of kilograms, obtain the

binding energy of the helium nucleus.


172/173

u0304.0u0026.4u0330.4 m

MeV5.931u1

MeV3.28energyBinding


173/173

Documents

apphysicsbexamreview-090425125639-phpapp01