Transcript 1st Semester Exam Review2

st
1 Semester Exam
Review
Lab Equipment
Test tubes
Watch glass
Erlenmeyer flask
Beakers
Graduated cylinder
Triple beam balance
Lab Equipment
Which of the following
measure volume?
Lab Equipment
 Measuring
 First
Volume
read the
liquid at eye level
 Second, read the
volume at the
curve of the
meniscus.
MEASUREMENTS

What is this measuring device
called?
Graduated Cylinder

What is it used to measure?
Volume of liquids

What is the curved line called?
Meniscus

What is the measurement?
50 .0 mL

Which is more precise: a
graduated cylinder or a
beaker? Why?
Graduated cylinder is
more precise because it
measures in smaller
intervals.
Lab Equipment
Which of the following
measure mass?
MEASUREMENTS




1. What is this
measuring device
called?
_______________
Triple Beam Balance
2. What is it used to
measure?
Mass of solids
_________________
3. What is the
measurement below?
___________
365.4 grams
4. What are the
correct units?
________________
Grams (g)
Precision vs Accuracy

What is precision?


Precision indicates how close together or how
repeatable the results are. A precise measuring
instrument will give very nearly the same result each
time it is used.
What is accuracy?

Accuracy indicates how close a measurement is to
the accepted value. For example, we'd expect a
balance to read 100.00 grams if we placed a
standard100.00 g weight on the balance. If it does not,
then the balance is inaccurate.
MEASUREMENTS
1.
Which of the
following is
more precise?
Why?
The first one is
more precise
because it
measures in
smaller
intervals.

A student measured the length of a piece of
string that was 64.34 cm long. Her
measurements were 64.32 cm, 64.34 cm, 64.35
cm, and 64.34 cm. Which of the following
statements is true?
 The measurements were accurate but not
precise.
 The measurements were precise but not
accurate.
 The measurements were both precise and
accurate.
 The measurements were neither accurate nor
precise.
Lab Safety

General guidelines
Safety first! Your main responsibility
in lab is to prevent injuries of yourself
and your partners!!
 Never work alone.
 Always read the directions before
starting the lab.
 Know where all safety equipment is
located and emergency contact
numbers.
 No eating and drinking in lab (or tasting
the chemicals!)
 Report ALL accidents to teacher.

Lab Safety continued….


Eye protection and Clothing
Before starting lab, tie back long hair,
roll up sleeves.
 Put on any protective equipment that
teacher requires:
• Ex: apron, lab coat, goggles, gloves,
closed-toe shoes, etc.)

Always wear approved GOGGLES
while in lab…**even if you are NOT
conducting an experiment at the
time.
 No contact lenses in lab
 The eyewash is available to rinse out
hazardous chemicals in the eye.
Disposal Safety
 AVOID
 Use
HAZARDS
caution when handling hot
glassware.
 When diluting acid, always add
acid slowly to water. Never add
water to acid.
 Always read the directions or
consult your MSDS when
disposing chemicals!!
During
a lab activity, isopropyl
alcohol is splashed into a
student’s eyes. What should the
student do?
A
Run to the nurse’s office
B Put on safety goggles
C Flush eyes with water
D Wipe eyes with a cloth
Scientific Method

How many
Data Trends

How many students
do you predict will
have a cell phone by
the year 2009?




15 thousand
18 thousand
19 thousand
20 thousand
Hypothesis

What is a hypothesis?
A
hypothesis is an educated
guess that can be tested by
experimentation.
Theory
 What
is a theory?
 An
explanation of things or
events based on many
observations.
 Can it be changed?
• YES!! It can be changed as
new data uncovers new
information.
 Which
statement is true about a
theory?
 A.
A theory can not be changed
according to new data.
 B. A theory does not have to be
repeated, because it based on only
one observation.
 C. A theory is an explanation of
things and events based on many
observations.
 D. A theory is can never become a
Speed is how fast you are
going.
Units: meters per sec (m/s)
Position vs time graph
 The
position vs time
graph shows where
things are at
different times
 Speed
is the slope
of the position vs
time graph
5 secs
275 m
150m / 5 sec =30 m/sec
speed
time
position
14 m
14 m / 4 sec = 3.5 m/s
speed
speed
B
A
Acceleration &
Momentum
 rate
at which
speed changes

What is
acceleration?
 Rate
of change
means the ratio
of the amount of
change divided
by how much
time it took to
change
 Formula
2nd velocity
1st velocity
vf – vi
t
time
 Unit
2 or
of
cm/sec
m/sec2
 Units
 Positive
acceleration
(speeding up)
 Deceleration
(slowing down)
 Zero
acceleration
(constant speed)

Acceleration
is the slope of
the speed vs.
time graph
DON’T WRITE
 What
is
momentum?

Mass in motion
Momentum
p=mv
Mass (g)
 Units
 kg
m/s
Velocity (m/s)
A
force is a push
or a pull
What
is
force?
F = ma
Force
(N)
Mass
(g)
Acceleration
(m/s2)
Acceleration due to gravity
(9.8 m/sec2)
Weight Force (N)
Fw = m g
Mass (kg)
• Gravity
(g) is a force that pulls every
mass toward the Earth; its different
depending on your planet.
• Earth g=9.8 m/sec2 (ALWAYS!!!)
• Mars g=3.8 m/sec2 (ALWAYS!!!)
Kinetic Energy
 What
is kinetic
energy?
 Energy
of motion
Potential Energy
 What
is potential
energy?
 Stored
energy
?
?
?
Law of Conservation of
Energy
 What
does the Law of
Conservation of Energy state?
Energy
can never be
created or destroyed – it
can only be turned into
another form.
Electricity

A circuit is a continuous loop that
provides a pathway for electricity to
travel through. There are 2 types:

Open circuits: an open circuit is a circuit
that has a break in it.
• An open circuit is said to be ‘turned off.’

Closed circuits: a closed circuit has no
breaks in it and therefore the electrical
current is flowing in a closed circuit.
• A closed circuit is said to be ‘turned on.’
Electricity
Battery
Switch
Resistor
Electricity
In a series circuit there is
only one path for the current.
If a light burns out in a series
circuit all the lights will go out.
In a parallel circuit the
current can flow in more
than one path. If a light
burns out in a parallel
circuit the others will not
go out.
Electricity
Law of Conservation
of Energy
Energy
can never be
created or destroyed – it
can only be turned into
another form.
How much current
would be measured in
the circuit below if
each resistor had a
resistance of 5 ohms?
I=V/R
I= 6v/ 2* 5 Ω
I= 0.6 amps
Heat Transfer
Three
mechanisms for heat
transfer
• Conduction
• Convection
• Radiation
Heat transfer

Conduction – heat transfer by direct contact of
particles EX.- Spoon in hot cup of coffee

Convection – transfer of heat by bulk movement
of fluid and gases EX- radiator, sea breeze

Radiation – heat transfer in the form of waves
EX.- Light, microwaves, radio waves, x-rays
Thermal Energy
is
the total energy of
the particles in a
material – both kinetic
and potential
Greenhouse effect

The greenhouse effect is the warming of Earth
due to carbon dioxide and other gases in the
atmosphere. Warming occurs as sunlight strikes
the Earth. Much of the sunlight is reflected back
into space. But Earth's atmosphere absorbs much
of the heat and slows its escape from Earth. In
this way, the Earth is like a greenhouse. The
atmosphere encloses the Earth just as panes of
glass enclose a greenhouse.
transverse
Transverse Waves
Transverse wave: has its oscillations
perpendicular to the direction of the
wave. The wave moves left to right
and the oscillation moves up and
down
 Ocean waves are transverse waves

longitudinal
Longitudinal Wave
Longitudinal wave: has oscillations in
the same direction the wave moves.
 Sound is a longitudinal wave

Parts of a Transverse Wave

What are the parts of a
transverse waves?

Crest
• The highest point of a wave
CREST

Trough
• The lowest point of a wave
REST POSITION
TROUGH

Rest Position
• The resting position from
which other things are
measured
Speed
Speed describes how fast the wave
moves
 Speed is frequency (f) times
wavelength (l)

v  fl
Speed (m/sec)
Wavelength (m)
Frequency (hz)
Reflection: bounce off
and goes in a new
direction.
 Refraction: bends as it
crosses the edge

Ripple Tank

Diffraction: bends as it
goes around a corner or
through an opening

Absorption: amplitude gets
smaller and smaller as it
passes through the
material
Tacoma
Resonance



Resonance occurs when a force exerted
on an object exactly matches the natural
frequency of the object
When resonance occurs only a small
force is needed to get a large response.
If you shake a string at the right
frequency, if makes a big wave motion.
If your frequency is not just right, the
string will not make a wave pattern at all
Formula Cheat Sheet