77 terms

Physical Science Final

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scientific method def.
process of using logic to solve a problem
1. determine the problem 2. research and observations 3. form a hypothesis 4. experiment 5. analyze data 6. draw a conclusion 7. report results to teacher and classmates
scientific method
observation
using one or more of your five senses to gather information
hypothesis
a testable statement "educated guess"
controlled experiment
experiment based on the comparison of a controlled group and an experimental group
independent variable
the 1 factor different between controlled group and experimental group
dependent variable
change that occurs due to the independent variable
constants
the factors that are the same between the control group and the experimental group
data
specific information based on observations
frame of reference
something you compare a moving object with to detect the movement
distance is how far something moves and displacement is distance and direction from a starting point
distance vs. displacement
vector
an arrow used to represent a force, displacement and acceleration
speed
the rate at which an object moves from one place to another
velocity
the speed and direction of an object
acceleration
a rate of change in velocity-speeding up, slowing down, changing direction
speed up
positive acceleration?
slow down
negative acceleration
force
a push or pull
balanced force
forces are of equal size and in opposite directions
unbalanced force
when forces are not equal in size
net force
total force applied to an object
centripetal force
the force exerted towards the center of a circle or curved path
friction
a force that acts in the opposite direction of motion between two objects in contact
gravity
the force of an attraction between any two objects
terminal velocity
when a falling object can no longer accelerate due to its air resistance
1. an object in motion tends to stay in motion until an outside force acts on it 2. force equals mass times acceleration 3. for every action there is an equal and opposite reaction
newton's 3 laws of motion
mass vs. weight
mass is the number of particles your body takes up and weight is the gravitational force of an object
inertia
tendency of an object to resist a change in motion
momentum
how much force is needed to change an objects' motion
fluid
any substance that flows including liquids and gases
air resistance
friction between air and an object
energy
anything that causes a change in its environment. ability to do work
kinetic energy
energy of motion
mechanical energy
number of times a machine multiplies its effort force to overcome resistance force
potential energy
stored energy due to position
thermal energy
the sum of the kinetic energy and potential energy of all the particles that compose an object
radient energy
energy carried by electromagnetic waves
temperature
a measure of the average kinetic energy of the particles that make up the object
heat
thermal energy that is transferred from something at a higher temperature to something at a lower temperature
specific heat
amount of heat energy required to raise the temperature of 1 kg of substance 1 degree celsius
convection
transfer of heat through a fluid by rising and falling currents
conduction
the transfer of heat by direct contact
radiation
transfer of heat by electromagnetic waves through empty space
conductor
any material that allows heat to travel through it; a low specific heat
insulator
poor conductors of heat
power
rate that work is done
work
when a force moves an object over a distance
effort force
force applied to the machine
resistance force
force in which effort must overcome in order to do work on an object
work input
work that goes into a machine
work output
work done by the machine
machine
instrument that makes work easier
simple machine
machine that does work with one movement
lever, pulley, wheel and axle, inclined plane, wedge, screw
6 simple machines
fulcrum
the point on which a lever rests and where it pivots
lever
a bar that is free to pivot on a fixed point
1st class lever
increases your force, distance, changes your direction or none of the above. fulcrum is in the middle
2nd class lever
always increases force. resistance force is in the middle
3rd class lever
always increases distance. effort force is in the middle
pulley
a grooved wheel with a rope or chain running along the groove
fixed pulley
does not increase force; changes direction of the force
moveable pulley
increases force, doesn't change direction
block and tackle pulley
combination of fixed and moveable pulleys, increases force, may or may not change direction
wheel and axle
two circular objects of different sizes that rotate together
inclined plane
a sloping surface used to raise an object; doesn't move and creates a longer distance for force to be moved over
screw
inclined plane wrapped in a spiral shape around a cylinder
wedge
a moving inclined plane with 1 or 2 sloping sides
mass of the objects and the distance between them
What 2 things influence that amount of gravity on an object?
static, sliding, rolling
What are the 3 types of friction?
static friction
friction between 2 surfaces that are not moving past each other
sliding friction
friction between 2 surfaces sliding past each other
rolling friction
friction between rolling objects
watt
What is the unit for power?
newton
What is the unit for force?
joule
What is the unit for work?
9.8 m/s/s
What is the gravitational force of earth?
type of surface and the weight
What 2 factors influence the amount of friction between 2 surfaces?