Scientific Method: a way of answering questions about the world
¬¬1. State the Problem
¬¬2. Collect Observations
¬¬3. Search for Scientific Laws
¬¬4. Forming hypothesis
¬¬5. Test hypothesis with Experiments
¬¬6. Forming theories
¬¬7. Modifying theories
Scientific Method Continued
¬ ¬ Hypothesis
–
– MUST
be testable
–
– Carefully
devised procedure for making observations and collecting data
¬ ¬ Variable: Factor that is being tested
¬ ¬ Experimental
Control: responds in an expected way
¬ ¬ Natural Law:
Draws together the results of many observations and experiments
¬ ¬ Theory: Explains what the results mean
Measurement
Quantity:
Definition Measure Units
with
Mass:
the quantity of a substance Balance g, kg, mg
Length:
longest side of an object ruler m,
cm, mm, km
Volume:
the amount of space Graduated
L, mL = cm3
taken up by something cylinder
Temperature: the degree of thermometer
Celcius ( C ),
hotness or coldness Kelvin
( K )
Matter
• • Matter: Anything that has mass and volume
• • Inertia: the tendency of things to resist changes in
motion
– – Mass is the measure of
inertia: the more mass the more inertia
• • Is it easier to stop truck or a
bicycle?
• • Is it easier to turn a canoe or a
cruise ship?
• • Weight: The gravitational force exerted on an object
by the nearest massive body (locally Earth)
Sure + 1
• • When recording
measurements, record to one digit more than the smallest increment on the
measuring device
Reliability
The Reliability of a measurement is determined by:
• • ACCURACY: how
close the measured value is to the true or expected value
• • PRECISION how
close the measured values are to each other when the measurement is repeated
Factor Label
•
• Used to convert from one unit into another. Ex. From mg
to g, or m/s to km/hr
•
• Also known as dimensional analysis.
•
• If the units cancel out and leave you with the proper
unit in the answer, you know you did it correctly!
How many dozen are 387 eggs?
• • Start by writing
the known quantity, with appropriate units.
• • Write the
conversion factor that represents the relationship between the given quantity
and the quantity you want to convert into.
• • Make sure that
the unwanted conversion factor unit will cancel out the given unit (conversion
factor needs eggs in denominator.
387 eggs = how many dozen?
387 eggs x 1 doz = 32.25 dozen
12 eggs
Density
ü ü Density: amount of mass per unit volume
Density = mass
D = m Units =g/mL or g/cm3
volume V
ü ü Measures
how closely packed together the atoms and molecules are
Low Density – loosely packed
High Density – packed close together
ü
ü More dense
objects sink.
ü
ü Less dense
objects float.
ü
ü Water has
a density of 1.0 g/mL.
Measuring Volume
• • Can be measured
directly, calculated or determined by water displacement.
Liquid Volume
• • Can be measured
directly
• • Pour into
graduated cylinder
– – on a flat surface.
– – read the cylinder at eye level.
Volume of a Regular Solid
• • Can be Calculated
from length measurements (cm)
V = l w h
for a rectangular solid
Water Displacement
•
•
Used to find volume of a small, irregular
solid.
Put some water in a graduated cylinder and measure
volume. Lower the object into the
graduated cylinder and determine the volume of the solid object.
Vsolid = Vsolid
+ H2O - V H2O
Water Displacement by Overflow
• • Used to find
volume of larger objects
• • Fill a container
to the top with water, lower the object into the water, and catch what
overflows.
Vsolid = Voverflow