Lab Equipment Which of the following measure volume?
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Lab Equipment Measuring Volume First read the liquid at eye
level Second, read the volume at the curve of the meniscus.
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MEASUREMENTS What is this measuring device called? What is it
used to measure? What is the curved line called? What is the
measurement? Which is more precise: a graduated cylinder or a
beaker? Why? Graduated Cylinder Volume of liquids Meniscus 50.0 mL
Graduated cylinder is more precise because it measures in smaller
intervals.
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Lab Equipment Which of the following measure mass?
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MEASUREMENTS 1. What is this measuring device called?
_______________ 2. What is it used to measure? _________________ 3.
What is the measurement below? ___________ 4. What are the correct
units? ________________ Triple Beam Balance Mass of solids 365.4
grams Grams (g)
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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.
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MEASUREMENTS 1.Which of the following is more precise? Why? The
first one is more precise because it measures in smaller
intervals.
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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.
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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.
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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.
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Disposal Safety AVOID HAZARDS Use 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!!
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During a lab activity, isopropyl alcohol is splashed into a
students eyes. What should the student do? A Run to the nurses
office B Put on safety goggles C Flush eyes with water D Wipe eyes
with a cloth
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Scientific Method How many
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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
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Hypothesis What is a hypothesis? A hypothesis is an educated
guess that can be tested by experimentation.
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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.
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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 law.
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Units: meters per sec (m/s) Speed is how fast you are
going.
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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
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5 secs 275 m 150m / 5 sec =30 m/sec speed
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time position 14 m 14 m / 4 sec = 3.5 m/s speed
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B A
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Acceleration & Momentum
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rate at which speed changes Rate of change means the ratio of
the amount of change divided by how much time it took to change
What is acceleration?
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Units of cm/sec 2 or m/sec 2 v f v i t 2 nd velocity1 st
velocity time Formula Unit