Download Study Guide Physical Science Mid-term Lab Safety If a student does

Study Guide
Physical Science Mid-term
Lab Safety
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If a student does not understand directions in the lab, get the teacher.
Scientific Theories vs. Laws
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Scientific Law – A rule that describes a repeatable pattern in nature. Ex. – If you drop a ball, it
will go down to the ground every time.
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Scientific Theory - An explanation of observations or events that is based on knowledge gained
from many observations and investigations – It explains the why or how something occurs.
Science + Society
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The three branches of science – Life, Earth, Physical
Metric Measurement
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Meter – unit of length
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Kilo – 1000
Scientific Inquiry
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Lab tools used by scientists – thermometer, meter stick, triple beam balance, computer
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Test Variable (independent) – The factor you want to test or manipulate in an experiment.
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Outcome Variable (Dependent) – How the variable is being measured.
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Constant – Factors in an experiment that do not change
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Control – A factor in an experiment that is purposely kept the same and used for comparison.
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Why do scientists do controlled experiments?
1. Collecting data
2. Trying to support hypothesis
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To evaluate observations you make, you use critical thinking skills
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After the experiment, scientists organize and analyze the data.
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Repetition – Making multiple sets of measurements or observations in a scientific investigation.
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Replication – The reproduction of a scientific investigation by another person to ensure accuracy.
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Graph – X axis = test variable and Y axis = outcome variable
Motion
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Motion- the process of changing position
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Displacement – the difference between the initial position and the final position
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Reference Point – A starting point used to locate a place or thing.
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Calculate motion - Use distance- time graphs
Speed
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Speed-distance traveled divided by time taken to travel the distance (km/Hr)
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Average speed- total distance traveled by an object divided by total time needed to travel –
ex. –what if it takes 10 minutes to drive 5 km?
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Instantaneous speed – a speed at any instant in time. (Ex – a car’s speedometer)
Velocity
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Velocity-speed in a given direction- ex.-A storm moving 15 km/hr, north.
Acceleration
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Acceleration – a change in velocity over time
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Determine acceleration – Use speed - time graphs
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Be prepared to identify the meanings for Distance-Time graphs and Speed-Time graphs
(Chapter 1, lesson 3)
Force
Force is measured in Newtons
Friction – A contact force that resists motion. Ex – a skater slowing down on the ice.
Friction causes thermal energy when the two surfaces interact.
Static friction – must be overcome to start an object moving
Gravity – a non-contact force. Ex – a ball falling
Gravity, magnetism and electricity are non-contact forces because they can act from a distance.
Newton’s First Law – Law of Inertia – An object in motion tends to stay in motion; an object at rest
tends to stay at rest.
If gravity did not affect the path of a horizontally thrown ball, then the ball would continue to travel
horizontally.
Newton’s Second Law – Unbalanced Forces –
Acceleration = Net Force/Mass
Newton’s Third Law – For every action, there is an equal and opposite reaction. Ex. – Newton’s Cradle
When we walk forward, the ground pushes back on us and we can move. It is pushing back with an equal
force from the opposite direction.
When an arrow is used to demonstrate force, the length of the arrow represents the strength of the
force.
Centripetal Force – a force that acts perpendicular to the direction of motion, toward the center of the
circle. Ex – swinging a bucket of water, or keeping a satellite in orbit.
When an object is falling through the air, air resistance applies an upward force.
Balanced vs Unbalanced Force
Balanced forces are equal in size but opposite in direction. (They combine to form a net force of zero)
Ex - A book sitting on a table
Unbalanced forces are forces that are unequal in size and may or may not be equal in direction. It will
cause an object to accelerate when it speeds up (+), slows down (-), or changes direction. Ex - an
elevator traveling up or down.
Net Force –The sum of all the forces acting on an object.
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Be prepared to identify examples.
Contact vs Noncontact Force
Contact force - A push or pull on one object by another that is touching it.
Noncontact force - A force that one object can apply to another object without touching it.
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Be prepared to identify examples.
Weight vs Mass
An object’s weight is proportional to its mass.
Weight is the effect of gravity’s pull on an object while mass is the amount of matter it contains.
Volume is the amount of space something takes up.
Matter - anything that has mass and takes up space.
Density is mass divided by volume = grams per cubic centimeters D= m/v = g/cm3
Electricity and Magnetism
Attraction - Describes the electric or magnetic force exerted by oppositely charged objects.
Conductor – A material in which electrons can easily move.
Insulator – A material in which electrons cannot easily move.
Magnet – any object that attracts the metal iron.
Ferromagnetic elements – iron, nickel, and cobalt that have an especially strong attraction to magnets.
Electromagnet – a magnet created by wrapping a current-carrying wire around a ferromagnetic core.
Forces in Fluid
A fluid is any substance that can flow and take the shape of its container. (liquid and gas)
Pressure – The amount of force per unit area applied to an object’s surface.
Atmospheric Pressure – The ratio of the weight of all the air above you to your surface area.
Buoyant Force – An upward force applied by a fluid on an object in the fluid.
Drag Force - A force that opposes the motion of an object through a fluid.
Short essay prompt:
Write a short persuasive essay on the importance of science. Use 10 vocabulary words in context and
underline them. (minimum of 10 sentences)
I should be able to determine what it is about science that interests you as you are persuading others to
appreciate it.