PCC Physical Science (SC 212) Mrs. Johnson Midterm

Science

"the study of God's order and reasonableness in the physical universe"

What is science limited to?

the physical and observable

4 steps of scientific method

1. formulating a problem

2. observation & experimentation

3. interpretation

4. testing the interpretation

speculate / hypothesize

formulating a problem

build / test models

make predictions / measure results

observation and experimentation

refine / expand hypothesis

producing further predictions

interpretation

evaluate hypothesis

lead to further observation / experimentation

testing the interpretation

science cannot ____ anything or bring absolute ____

prove, truth

length

meters

mass

kilograms

time

seconds

work

joules

power

watts

combined units are called ____

derived units

where is uncertainty found in significant figures?

last measured unit

how many significant figures are in the number 1,012?

four

how many significant figures are in the number 0010,128?

five

how many significant figures are in the number 1,000?

one

how many significant figures are in the number 1000.00?

six

When adding/subtracting decimals, find the number with the least amount of ____ places and round the answer according to that.

(Example: 9.1 + 10.72 = 19.5)

decimal

the rate (time) at which a distance is covered

speed

how is speed written?

m/s

speed at a given moment

instantaneous speed

formula for average speed

v = d/t

____ speed can't be measured

instantaneous

what are the only two ways to rewrite

V = D/T?

D = VT

T = D/V

measures magnitude only

scalar

measures both magnitude and direction

vector

which three units are scalar?

speed, distance, energy

which three units are vector?

displacement, velocity, momentum

vectors can be rewritten as ____ and ____ components

parallel and perpendicular

use the ____ theorem to add perpendicular components

pythagorean

change in velocity (speed) over time

acceleration

three characteristics of acceleration

slowing down

speeding up

changing direction

acceleration in the opposite direction of motion

negative acceleration

formula for acceleration

a = (v2 - v1)/t

in a free fall, acceleration is ____

constant

____ acceleration is the same for all falling projectiles

downward

free fall on earth

9.8 m/s

slows down certain objects

air resistance

projectile paths are shaped like ____

parabolas

as objects fall ___, the the force of air resistance increases

faster

speed at which the force of gravity and the force of air resistance are equal

terminal speed

causes acceleration

force

an object at rest remains at rest and an object in motion stays in motion unless acted on by an unbalanced force

first law of motion

A force is any ____ or ____

push, pull

produces a net force and an acceleration

unbalanced forces

the property of matter that shows itself as interia

mass

the reluctance of an object to change its state of motion

inertia

the net force of an object equals the product of the mass and the acceleration of the object

second law of motion

net force formula

f = ma

increasing force will ____ acceleration

increase

___ mass will increase acceleration

decreasing

direction of the force is the ____ as acceleration

same

earth's attractive force on an object

weight

____ mass = more weight

more

mass is ___, but weight is not

constant

when an object exerts a force on a second object, the second object exerts an equal force in the opposite direction on the first object

third law of motion

force on the passive object

action force

force pushing back

reaction force

the inward force on an object moving in a curved path

centripetal force

change in direction caused by centripetal force

centripetal acceleration

every object in the universe attracts every other object

newton's law of gravity

newton's law of gravity formula

F = g (m1 x m2) / r^2

force is ___ proportional to distance

inversely

____ is done when a force causes a change in an objects position

work

formula for work

w = fd

a force only works if it has a component in the direction of ____

motion

the rate of doing work

power

formula for power

p = w/t

work is the transfer of ____ energy

mechanical

the energy of an object's motion

kinetic energy

kinetic energy is directly related to the mass of an object and to the ____ of the speed

square

the ____ something is moving, the more kinetic energy it has

faster

kinetic energy formula

ke = 1/2 x mv^2

the energy stored in an object's position

potential energy

the amount of work that can be done by an object falling

gravitational potential energy

formula for potential energy

pe = mgh

less ____ equals less work

height

energy can't be created or destroyed but it can be changed from one form to another

conservation of energy

the amount of energy in the universe is ____

constant

lost mechanical energy is lost as ____

heat

heat is dissipated energy through the surrounding atoms

work-energy theorem

a device that changes the magnitude of the force

simple machine

a simple machine can't create ____

energy

simple machines multiply force at the expense of ____

distance

how much the force is multiplied

mechanical advantage

mechanical advantage is the ratio of ____ force to ____ force

output, input

rigid bar on a fulcrum (pivot point)

lever

increases / decreases force (ex: pliers or scissors)

class 1 lever

in class 1 levers, the ____ is in the middle

fulcrum

only increases force (ex: wheelbarrow or nutcracker)

class 2 levers

in class 2 levers, the ____ is in the middle

output

only decreases force (ex: tongs or staplers.. even arms!)

class 3 levers

in class 3 levers, the ____ is in the middle

input

____ and ____ are circular levers

belts, gears

ramp that allows a smaller force to be applied at a greater distance

inclined plane

inclined plane wrapped around a rod (vice grip)

screw

people originally thought heat was a substance called ____

caloric

____ discovered that heat is a form of energy

Joule