Transcript Student notes Chap 1 & 2

Scientific Method 6 Basic Steps
• 1) State the __________
• 2) Gather information
• 3) Form a _______ (educated guess)
• 4) Test the hypothesis (________)
• 5) Analyze ______
• 6) Draw ________
Variable - quantity that can have
more than ________
• dependent variable - value changes
according to the ________ in the other
variables (ex. _________)
• Variable you ________ to see how it will
affect the ______ variable is called the
independent variable (ex. Time)
Terms
• Control – standard by which test results
are _______
• Constant – factor that ______ change in
an experiment
• Theory – explanation based on knowledge
from many _________ & _________
• _____ – statement about what happens in
nature (ex. Gravity)
Graph – visual display of _____
• _____ types
– Line
– Bar
– Circle or pie
Line graph
• Dependent _______ plotted on y axis
• Independent variable _______ on x axis
• Always _______ your graph
• Label both the x & y ______
• Use a ____ _____ when drawing a graph
• Make graph large enough to cover ______
¾ of the space provided
SI – international system of
_____________
SI Prefixes
• Based on multiples of
•
_______
______ units
– Gram (__)
– ______ (l)
– Meter (__)
Base units
• Meter – measures
•
•
________
Liter – measures
________
Gram – measures
_________
Density – mass per unit ______
• Mass - measurement of
the ________ of matter
in an object
• A bowling ball has a ____
of about 5,000g
• roughly 100 times greater
than _____ of a golf ball
& 2,000 times greater
than a table-tennis ball’s
mass
Amount of ______ occupied by an
object - volume
• To find volume of a ______ ______ (such as a brick)
• Measure its length, _______, & height
• Then multiply the ____ numbers & their units together
( V = 1 x w x h)
• (For a brick) measurements probably would be in
centimeters
• Volume would be ________ in cubic centimeters, cm3
Water Displacement Method – used
to find ______ of irregular solid
• 1) put _____ in graduated cylinder
• 2) ______ initial amount of water
• 3) gently add “irregular solid” ex. _____
• 4) Record final ______ level
• 5) ______ the water levels to determine
volume of the solid
• 6) volume will be expressed in _____ (ml)
Sample Problems – Volume
• 1) Each side of a cube is 2.8cm, what is the
volume of cube?
• 2) What is volume of a box that is 18.9cm long,
9.2 cm wide, and 3.1 cm high?
• 3) With 12.6ml of water in a graduated cylinder,
a rock is added and the water level rises to
18.3ml. What is the volume of the rock?
Density = mass/volume
• 1) What is the density of a box with a mass of
176g and a volume of 3.2cm3?
• 2) What is the volume of a liquid with a density
of 18.6g/ml and a mass of 96g?
• 3) What is the mass of an object that has a
density of 12.4g/cm3 and a volume of 4.31cm3?
Speed & Velocity
• Frame of ______ – needed to determine _____
•
of object ex. Sign post
Distance – change in _________
– SI unit – _______ (m)
– How far it has moved
• Speed – distance an object _____ per unit of
time
– Speed = distance/_______
– SI ___ – meter/second (m/s) or larger unit (km/h)
Speed S=d/t
• 1) A car traveling at a constant speed covers a
distance of 750m in 25s. What is the speed?
• 2) A passenger elevator operates at an average
speed of 8m/s. If the 60th floor is 219m above
the 1st floor, how long does it take the elevator
to go from the 1st to 60th floor?
S = d/t
• 3) A motorcyclist travels an average speed of
20km/h. If the cyclist is going to a friend’s house
5km away, how long does it take the cyclist to
make the trip?
• 4) An ant travels 75cm in 5s. What was the ant’s
speed?
• 5) It took you 6.5h to drive 550km. What was
your speed?
Average Speed
Average speed
• total distance traveled
•
_____ by the total
time of travel
total distance traveled
was 5 km and the
total time was 1/4 h,
or 0.25 h. The
average speed was
_______
Instantaneous Speed
• speed at a given ____
•
•
•
in time
Ex. Speedometer
speeding up or
slowing down –
_______ speed is
changing
_______ speed, the
instantaneous speed
_______ change
Displacement
• _____ & ______ of an
object's change in
position from the starting
point
• length of the runner's
displacement & the
distance traveled would
be the _____ if the
runner's motion was in a
single direction
Motion
• ______ of an object
•
•
over a period of time
can be shown on a
distance-time graph
Time – plotted on
________ axis
Distance traveled –
plotted on vertical
___
Graphing Motion
Velocity = distance/____
• speed of an object &
•
•
the _____ of its
motion
velocity of an object
___ ____ even if the
speed of the object
remains constant
SI unit – ______
Change in speed = change in _____ as long as direction remains the _____
___________
• Rate of change in _______
• Occurs when object changes ______,
direction, or BOTH
• _______ acceleration – speed increasing
• Negative acceleration – speed _________
Positive Acceleration
• acceleration is in the
same ______ as the
velocity – speed
increases
Negative Acceleration
• speed _______ – the
acceleration is in the
______ direction from
the velocity
Changing Direction
• speed of the horses in
this carousel is _____,
but the horses are
accelerating because
their direction is
_______ constantly
Calculating Acceleration
Calculating Velocity
Sample Problems
• 1) A jet starts at rest and at the end of
runway it has reached a speed of 80m/s in
20s.
• 2) Skateboarder moving in a straight line
at a constant speed of 3m/s and comes to
stop in 2s.
_____ – push or ____
• Sometimes ______
•
•
forces are obvious but
not always
can cause the ______
of an object to
change
force of moving ball
causes ball at rest to
move in the _______
of the force
Forces
• ___ force – 2 or more
•
•
forces acting on a
object @ same ____
zero because the ___
forces cancel each
other
Forces ____ in size &
_______ in direction –
balanced forces
________ forces
• 2 students pushing with
•
________ forces in
opposite directions – net
force occurs in the
direction of the _______
force
net force – will be the
__________ between the
two forces because they
are in opposite ________
Unbalanced forces
• forces are combined
•
(______ together)
because they are
exerted on the box in
the _______ direction
net force that acts on
this box – found by
_______ the two
forces together
Inertia – tendency of an object to
_______ any change in its motion
• If object is _______, it will have uniform
motion
• It will keep moving at the same _____ &
in same ________ unless acted on by an
unbalanced force
• velocity of the object remains _______
unless a force changes it
• object at ______ remains at rest
Inertia
• inertia of an object is related to its mass –
greater the ____ of object the greater its
inertia
• Sir Isaac ______ – stated rules that
describe the effects of forces on the
_______ of objects – known as Newton's
law's of motion
Newton’s ______ Law of Motion
• Also called the law of _______
• states that an object moving at a constant
velocity keeps moving at that _______
unless acted on by an unbalanced net
force
• object at rest stays at ____ unless acted
on by an unbalanced net force
law of inertia – explains what
happens in a car crash
• A car traveling about
50 km/h collides
head-on with
something solid, the
car crumples, slows
down, and stops in
about 0.1 s
law of inertia – explains what
happens in a car crash
• Any passenger not wearing a safety belt
continues to move _______ at the same
speed the car was traveling
• Within about 0.02 s after the car stops,
unbelted passengers slam into the
dashboard, steering wheel, windshield, or
the backs of the front seats
law of inertia – explains what
happens in a car crash
• force needed to slow a person from 50
km/h to zero in 0.1 s is equal to 14 times
the force that gravity exerts on the person
• belt loosens a little as it restrains the
person, increasing the time it takes to
slow the person down
• this reduces force exerted on the person
• safety belt also prevents the person from
being thrown out of the car