GRADE 8 PHYSICAL SCIENCE STUDY GUIDE FOR FINAL 2012

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GRADE 8
PHYSICAL SCIENCE STUDY GUIDE FOR FINAL

2012


NATURE OF SCIENCE BOOK


LAB RULES
, S
CIENTIFIC

M
ETHOD
,
METRIC SYSTEM


-
What are some general lab safety rules?

wear goggles, tie hair back, respect equip, read all directions, report all
accidents


-
Name the steps of the scientific method and describe each.


Problem
state the question


Research
gather background knowledge


Hypothesis
education question relat
ed to the problem question


Experiment
test your variable and collect data


Observation
using your senses


-
What is the control group?

standard to compare


-
In an experiment, what is the dependent variable? What is the independent variable?

Independent

Variable
what you are testing or changing

Dependent Variable
what is being measured


-
When would you use a line graph? A bar graph?

Line
compares changes over time

Bar
compares


-
Define and name metric units for:

length
distance for point to point



mass

amount of matter in an object

volume

amount of space an object takes up


-
What is the volume of a block of wood which is 10 cm x 20 cm x 30 cm?

600 cm
3


-
Where is the x
-
axis on a graph? Y
-
axis?

X axis is
across the bottom



y axis is
vertical

on the side


-
Where is the Independent and Dependent variable placed on a graph?

Independent
x axis
dependent
y axis


-
How are mass and weight different?

Mass is the
amount of matter in an object and never changes
, weight is
affected by gravity


-
How
do you find the mass of water on a balance?

Place an empty beaker on the balance, record its mass

Fill the beaker with water, record its mass

Subtract the difference that is the mass of the water


-
How do you find the volume of an irregular shaped object?

Place it in a displacement cup

Catch water in a graduated cylinder

Record volume in cm
3

by converting ml to cm
3


-
Know how to convert in the metric system

King henry does much damage cooking meals


-
What is density?

amount of matter per given volume


-
What

is the formula and units for density?

Mass/volume g/cm
3


-
What is the freezing and boiling point for water in degrees Celsius?

0° C and 100° C


-
Know correct measurements and units for:

Metric ruler

cm

graduated cylinder

ml

stop watch


s

thermometer


°C

spring scale

N


triple beam balance

g

meter stick

m



MOTION FORCES & ENERGY BOOK

-
What is motion?

the state in which on objects distance from another is changing


-
Know the difference between balanced and unbalanced forces

Balanced
: no movement

Unbalanced
: forces act upon it, ie. Gravity, friction


-
Define Newton’s First Law of Motion and give an example.

An object in motion will stay in motion, and object at rest will stay at rest unless and unbalanced force acts
upon it

Ex.

Gravity will pul
l objects down




Friction will slow objects down


-

Define Newton’s Second Law of Motion and give an example.

F= ma

The greater the mass the more force is needed to accelerate it a given distance


-

Define Newton’s Third Law of Motion and give an example.

For every action there is an equal and o
pposite

reaction

The car tire push on the ground, the ground pushes on the tires


-
Formula and units for Speed

distance

( m/s )


Time


-
Define constant speed


the speed of an object does NOT change



-
Define
average speed

the speed of an object is NOT constant over time


-
Define velocity

speed in a given direction


-
Define Acceleration

change in velocity over time in science it is speed up, slowing down or changing direction


-
Give examples of objects acceler
ating

When you press on the accelerator of a car, it moves forward

A skateboard going down a hill


-
What is centripetal motion?

object that is a continuously changing direction in a circular path (planets)



FORCES:

-
What is a force?
a push or pull



-
Defin
e:

Inertia
-

means that an object at rest will remain at rest until an outside force acts upon it

Gravity
-

a force of attraction between objects that is dependent on its mass and the distance between them

Friction
a force that opposes motion; will cause an
object to slow down


Sliding friction
friction produced when solid objects slide over each other

Rolling friction
friction

produced by objects such as wheels or ball bearings

Fluid friction
force of friction produced by a fluid such as liquids or gases

Static Friction
-

f
riction between two or more solid objects that are not moving relative to each other



WORK

-

Define work and give an example.

When is force is exerted to move an object a given distance


-
Formula and units for work
-
F x d
(

Joules
)


-
Jou
le is the unit used for:

Work, energy


-
9.8 m/s² represents what?

The rate at which all objects Accelerate due to gravity


BRIDGES

-
What are the

main types of bridges?

Beam bridge
longer beam, less strength
so real
ly only good for short distance
:compression on

top, tension
underneath

Truss bridge
uses triangles to strength the beam, good for railroad bridges

Arch bridge
strongest to withstand compression. Compression on sides, tension underneath, Romans

Suspension bridge
best for long spans,
and resisting tension


-
What is compression, tension, load, and deck?

Load; weight

on bridge: people, cars, other vehicles
,

Deck:
supported roadway of a bridge

Tension
a force that stretches a material apart

Compression
a

force that squeezes material together


-
Which bridge can span the longest distance?

suspension


-
Which bridge can span the shortest distance?

arch


-
What is the supporting lattice work that strengthens beam bridges? What shape is it? Why is it added t
o some
beam bridges?

Truss

Triangular

Supports both in tension and compression


-
Which bridge is strongest in tension? In compression?

Suspension





arch


Truss

triangular shape used to strengthen a beam bridge


Steel vs concrete used for construction

Steel vs concrete used for construction concrete , easy to construct quickly, lots of repair costs

Steel: easy to form to shape and repair (Painting helps avoid rust)


Load

weight

on bridge: people, cars, other vehicle

Deck

supported roadway of a brid
ge



SIMPLE MACHINES


-
Define simple machines

Any machine that makes work easier


L
ever

a rigid bar that is free to pivot or move about a fixed point called a fulcrum

Pulley

a rope, belt, or chain wrapped around a grooved wheel ex. Flagpole

Inclined
plane
a straight slanted surface ex. Staircase

Ramp

form of an inclined plane

Screw

A screw is an inclined plane wrapped around a pole which holds things together or lifts materials.

Wheel & axle
A

wheel with a rod, called an axle, through its center lifts or moves loads




HEAT TRANSFER

-
Define and give examples of :

Conduction
transfers
of heat or thermal energy by direct contact

Convection
t
ransfers through a heated liquid

or gases, creates co
nvection currents

Radiation
transfers
of heat energy through electromagnetic waves, does not need matter to transfer the energy

Temperature
Amount of kinetic energy, measured by the hotness of coldness of an object




ENERGY

-
What is energy?
the ability to w
ork


-
Compare potential and kinetic energy, and give an example of each.

Kinetic energy
energy of motion ex. Diver dives and is falling

Potential energy
energy of position or stored energy ex. Diver getting ready to dive off cliff


-
Define and give an
example of:

chemical energy

energy the energy of bonding of atoms Energy is stored in our bodies from food we eat

mechanical energy

the sum of potential and kinetic energy: moving energy ex. running water, sound

e
lectrical energy

the energy of moving
electri
c charges ex
. Turn on a lamp: electrons move through wires

electromagnetic energy

the energy of light ex. Sun, light bulbs

nuclear energy

energy stored in the nucles of an atom



Fission atoms split : earth



Fusion atoms join: stars

thermal e
nergy

heat energy, is the total energy of the particles in a substance


-
What is the Law of Conservation of Energy?

energy can neither be created nor destroyed but converted from 1 form to another


-
What energy conversions occur using a toaster?

: toaste
r: nuclear(sun) > Elect magnetic(light) > chemical potential (fossil fuel) > thermal (burn) > mechanical
(steam turns turbine) > electrical (turbine turns generator ) > thermal (toaster)


-
Define:

fossil fuels

coal, oil and natural gas formed millions of
years ago form the remains of dead plants and animals,
nonrenewable and have the ability to burn


turbine

like a fan with blades, the pressure of stream causes it to spin


generator

motors that produce electricity, magnets and coiled wires are needed


nonrenewable energy

energy that cannot be obtained in a short period of time


renewable energy

energy that can be obtained relatively quickly


biomass

renewable energy

from sources that can be replesnished in a short time


nuclear energy

nonrenewable
energy

obtained from splitting atoms such as uranium


solar energy

renewable energy from the sun


hydrogen fuel cell


wind energy

renewable energy

from the movement of the wind


hydroelectric energy

renewable energy

from moving water


geothermal energy

ren
ewable energy

from heat deep in the Earth


-
What is the purpose of generators spun by turbines?

To create electricity








MAGNETISM AND ELECTRICITY BOOK


Electricity

flow of
electric

charge



Static electricity

build up

of electric charges on the surface of a material.



Series circuit

One path for flow of e
-


Parallel circuit

the current can take several paths


Current

flow of electric chargess


Voltage

measure of
electric potential ex.

batteries: (9v 1.5 V)


Short c
ircuit

there is a break in the cirucit


Attract

opposite poles

Repel

like poles


Insulator

stops the flow of heat or electricity


Conductor

easily transfers energy in the form of electricity and/or heat


Know the advantages and disadvantages of:

Incandescent
lights

bright, hot, not energy efficient


Fluorescent
lights

energy efficient, contain
mercury


LED
lights

small, energy efficient, not bright


Draw a simple circuit



Magnetism

Any material that attracts iron and materials that contain
iron

Attract or repel other magnets

One part of a magnet will always point north when allowed to swing freely


Magnetic domain

region around magnet where they are aligned


Magnetic field

The area of the magnetic forces is known as the magnetic field


Ferro
magnetic material

A
ny

material that contains iron


Magnetic pole

The ends of the magnet
, where the effects are the strongest

area around the magnetic that have the strongest charge





What is the
ind
ependent variable on the
above
graph?

Time (s)




Nick Nack rode his bicycle to Patty Wack’s

house. The graph above matches his motion. What was his
average speed for the trip??

1400/10

140 m/min

Tricycle Travel


Time (minutes)

Distance Traveled (m)

1

3

2

6.5

3

8.4

4

12.5

5

14.0


Jake’s Mom used a ruler to measure the
distance he traveled riding his new tricycle. What was Jake’s
average

speed for these five minutes?

14/5 = 2.8 m/min

Nick Nack ‘s Distance Versus Time


0

200

400

600

800

1000

1200

1400

1600

1800

2000

0

1

2

3

4

5

6

7

8

9

10

Time (min)

Distance (m)

(m)



∙∙ ∙ ∙ ∙ ∙ ∙ ∙

Start


End



What do the dots on the ticker tape tell you about the speed of the object?

Acceleration or speeding up



If a man applies a force of 100N to a box down a hallway 50 m long. How much work has been

done?

1000 x 50 = 50000J


Is a person doing work on his backpack while walking home? Why or why not?

No, because he is not exerting a force on his backpack that is in the same direction as his walking


A lever is a bar that pivots on a (load, effort,
fulcrum).

fulcrum


Convert the following:



1mL =
.001
L








4200km =
4,200,000 m



820g =
820,000 mg







62.5cm =
.
625 m




1000g =
1 kg







Circle the most reasonable answer


thickness of a quarter

2mm





amount

of water a large jug may contain

3L





distance from your house to Westfarms Mall

25km


length of a pen


16cm