Physical Science Test One

first definition of science

knowledge about the natural world

second definition of science

a method for obtaining that knowledge

giving naturalistic explanations

explaining events using natural causes

believing in naturalism

beleif that only natural things exist

naturalism

not consistent with christianity

observations

science is always based on these

how observations are related to experiments

set up conditions where observations can be used to compare the predictions with the real world

hypothesis

generated by inductive reasoning

empirical

from experience

repeatable

happens multiple times and by others too

falsifiable

there is a way to figure out if its true or false

why science is never 100% certain

error and impercision, nothing is 100% certain in science, based on observations

control

something that stays constant throughout each trial

independent variable

what you are testing or the cause

dependent variable

what you are observing or the effect

independent, dependent

variable on the x-axis, variable on the y-axis

data

careful observation, called fact if repeatable, more objective, should take priority

theory

possible explanation for observation, supported hypothesis, answers why

trust data more

what scientists trust more, data or theory

2 parts of a measurement

number and unit

quanitative

using numbers

why we need consistent units

so everyone can use the same unit and know it

fundamental units

can’t be broken down into simpler quanities or measurements

only units

what do unit conversions affect

motion

a change in position over time

fundamental units

distance and time

d/t

formula for velocity

acceleration

a change in velocity (in magnitude or direction)

units of acceleration

meters per second squared

inertia

an object in motion tends to stay in motion; an object at rest tends to stay at rest, unless acted upon by an outside force

Galileo

who first described inertia

how inertia is related to acceleration

no acceleration without an outside force (push or pull)

newtons first law

inertia principle

newtons second law

force = mass x acceleration

newtons third law

whenever one object exerts a force on a second object, the second object exerts and equal and opposite force on the first

mass

the quanity of matter in an object (and its measurement of its inertia)

weight

the force of gravity acting on an object

weight changes

does inertia or weight change based on location

9.8 m/s2

the acceleration caused by gravity on the surface of the earth

why all objects don’t fall at exactly the same rate

the less mass an object is, the more the force of air resistance slows the object down as it falls

terminal velocity

maximum speed an object can reach while falling through a fluid or a medium

how newtons third law described our bouncing ball lab

the Earth exerted a force on our ball, causing it to bounce back up

first reason newtons laws don’t always work

when an object moves near the speed of light (einsteins special relativity)

second reason newtons laws dont always work

when an object is under the influence of very strong gravitational forces (einsteins general relativity)

third reason newtons laws don’t always work

when an object is incredibly small, on the atomic scale or even smaller (quantum mechanics)

what is remarkable about newtons universal law of gravitation

first to recognize that the same force that pulls dropped objects towards earth, also keeps the moon in motion around the earth

mass and distance

what two things affect the force of gravity between two objects

newtons cannon

if you shoot a cannonball faster, it travels further before it falls to the ground. if the cannonball goes fast enough, its fall height equals the curvature of the earth, and it will become a satellite of the earth.

satellite

an obkect that covers 8 km/s which is equal to about 23 times the speed of sound

why satellites don’t crash to earth

it will orbit earth in an ellipse shape

density

the ratio of mass of an object or sample to its volume

d = m/v

density equation

fluid

any form of matter in which particles don’t have a fixed position

gases and liquids

two common states of matter that are fluids

pressure

force acting over an area

no they dont

do equal forces always apply equal pressure

pressure increases

as you go deeper/lower what does pressure do in a fluid

buoyant force

upward push a fluid exerts on an object submerged in it

cause of buoyancy

the deeper the particles are under more pressure so they exert a stronger pressure pushing up than higher particles pushing down

archimedes principle

principle that defines what buoyancy equals

1 g/ml

density of water

energy

capacity to do work

work

transfer of energy by applying a force over a distance

kinetic energy

energy due to the motion of an object or particle

potential energy

energy stored in a system in some way

mass and height

factors that affect potential energy

mass and velocity

factors that affect kinetic energy

thermodynamics

the study of heat and its transference

first law of thermodynamics

the total thermal energy of a system doesn’t change, aka the law of conservation of energy

second law of thermodynamics

heat flows from a higher temperature substance to a lower temperature substance with which it is in thermal contact

third law of thermodynamics

a systems entropy approaches a constant value as the temperature approaches absolute zero

entropy

a measure of energy dispersal/disorder

increase

does entropy generally increase or decrease

0 K

what is absolute zero

negative numbers or degrees

what doesnt kelvin have or use

what determines the temperature of an object

the amount of motion of the particles

what happens when objects of different temperatures come in contact

the higher energy molecules in warmer object collide with lower energy molecules in cooler object, transferring kinetic energy via conduction

absolute zero

the point where molecular motion, kinetic energy, and vibrations stop

conduction

moving particles collide with adjacent particles

convection

in a fluid, particles heat up and move away from heat source and cooler ones replace them

radiation

in the form of electromagnetic rays (light), all objects radiate energy waves at frequencies proportional to their temeprature

radiation

which type of heat transfer works through a vaccum

how temperature and density are generally related

at higher temperatures, molecules vibrate faster which means they tend to spread apart which means density decreases

how a thermometer works

when the bulb is heated, the liquid inside gains energy, expands, and becomes less dense

it gets less dense as it gets colder

what is unique about water and density