ENHANCED SCIENCEGRADE 7

(Reviewer)BY: Jimnaira U. Abanto

Science from Curiosity

OCuriosity is the basis of science. It provides questions but is seldom enough to achieve scientific results.

OScience is a system of knowledge and the methods you used to find that knowledge. And it begins with curiosity and often ends with discovery.

Science and Technology

O Technology is the use of knowledge to solve practical problems.

GOAL of Science and Technology

O Science is TO EXPAND KNOWLEDGE.O Technology is TO APPLY THAT

KNOWLEDGE

Branches of Science

Scientific Method

O It is an organized plan for gathering, organizing, and communicating information.

Goal: To better understand an observed event.

Make observation Ask question

Develop hypothesis

Test hypothesis

with an experiment

Analyze data and

Draw Conclusions

When you walk or run in the rain, you

get wet

How does your speed affect how wet you get when you are caught in

the rain?

You might predict that the faster your speed, the drier you will stay in the rain.

Variable- any factor that can change.Manipulated variable – the variable that causes a change in anotherResponding variable – the variable that changes in response to the manipulated variable.Controlled Experiment – is an experiment in which only one variable, the manipulated variable is deliberately changed at a time. While the responding variable is observed for changes, all other variables are kept constant or controlled.

Running in the rain keeps you drier than walking—

about 40% drier.

Theory & LawO Scientific theory

It is a well-tested explanation for a set of observations or experimental results. Theories never proved. Instead, they become stronger if the facts continue to support them. However, if an existing theory fails to explain new facts and discoveries, the theory may be revised to a new theory may replace it.O Scientific Laws

It is a statement that summarizes a pattern found in nature. And it describes an observed pattern in nature without attempting to explain it. The explanation of such a pattern is provided by a scientific theory.

MeasurementsO Using Scientific NotationScientific Notation is a way of expressing a value as the product of a number between 1 and 10 and a power of 10.Ex. 300,000,000—3.0 x 108

0.00086 --- 8.6 x 10-4

O It makes very large or very small numbers easier to work with.

O SI Units. Scientists use a set of measuring units called SI, or the International System Units.SI Base Units Derived Units

Quantity Unit Symbol Quantity Unit Symbol

Length Meter M Area Square meter m2

Mass Kilogram Kg Volume Cubic meter m3

Temperature Kelvin K Frequency Hertz(1/s) Hz

Time Second S Electric charge Coulomb(Axs) C

Amount of substance

Mole Mol Density Kg per Cubic meter Kg/m3

Electric current

Ampere A Pressure Pascal(kg/mxs2) Pa

Luminous intensity

Candela Cd Energy Joule(kgxm2/s2) J

SI PrefixesPrefix Symbol Meaning Multiply Unit

byGiga- G billion(109) 1 000 000

000

Mega- M million(106) 1 000 000Kilo- K thousand(103

)1 000

Deci- D tenth(10-1) 0.1Centi- C hundredth(10

-2)0.01

Milli- M thousandth(10-3)

0.001

Micro- µ millionth(10-6) 0.000001 Nano- N billionth(10-9) 0.00000000

1

O Conversion Factor is a ratio of equivalent measurements

that is used to convert a quantity expressed in one unit to another unit.

Ex. 8848 m to km

= 8.848 km

O Measuring TemperatureCommon Temperatures

  Fahrenheit(oF) Celsius(oC) Kelvin (K)Water boils 212 100 373

Human body 98.6 37 310

Average room 68 20 293

Water freezes 32 0 273

• You can convert from one scale to other by using one of the following formulas.

 

Significant Figures-- all digits, including the last number. The number of SF indicates the exactness of measurement.Guidelines:O All non-zero digits are significant. Ex. a. 29685 – 5 b. SF 286.9 = 4

SFO A zero that appears between two non-zero digits is significant. Ex. a. 206059 = 6SF b. 4.008= 4SFO Zeros that appear to the left of an understood decimal point but

the right or a non-zero digit are not significant(unless otherwise indicated)

Ex. 890,000,000 = 2SFO Zeros to the left of an expressed decimal point and to the right of

non-zero digit are significant. Ex. a. 5280=4SF b. 104800=6SFO Zeros to the right of a decimal point but to the left of a non-zero

digit are not significant. Ex. 0.00129 = 3SF O Zeros to the right of a decimal point and to the right of a non-zero

digit are significant. Ex. 0.0510 = 3SF 16.000= 5SF *In decimal numbers less than one, the zero that is placed to the left of the decimal point is never significant.

ASSESSMENT(Reviewing Content)

QuestionOThe application of knowledge to solve practical problems is known as

a. Scienceb. Curiosityc. Technologyd. Experimentation

QuestionOWhich is not a branch of natural

science?a. Physical Scienceb. Life Sciencec. Earth Scienced. Social Science

QuestionOWhat is the purpose of an

experiment?a. To communicate datab. To test a hypothesisc. To prove a scientific lawd. None of the above

QuestionOWhich value is equivalent to 5 x

106

a. Five thousandb. Five millionc. Fifty thousandd. Fifty million

QuestionOIn a controlled experiment, a. There are multiple responding

variablesb. The responding variable is kept

constantc. The manipulated variable is kept

constantd. The responding variable is

deliberately changede. Only one variable at a time is

deliberately changed

QuestionO The speed of an object indicates how far it

travels in a given amount of time. If an electron travels 2.42 x 108 meters in 2 seconds, what is the speed of this electron in cm/s?

a. 1.21 x 108 cm/sb. 4.83 x 108 cm/sc. 1.21 x 1010 cm/sd. 2.42 x 1010 cm/se. 4.84 x 1010 cm/s

QuestionOA doctor measures the temperature of

a patient to be 101 oF. What is this temperature in kelvins?

a. 38.3 Kb. 214 Kc. 346 Kd. 73.8 Ke. 311 K

QuestionO A student conducts an experiment by dropping a

basketball and a box of cereal of the same weight from the top of a building. The student measures the time it takes for each object to strike the ground. What was the student’s hypothesis?

a. A basketball weighs more than cerealb. Curved objects travel through the air faster than the

flat objectsc. Heavier objects travel through the air faster than the

lighter objectd. Gravity pulls on objects of the same weight with the

same forcee. Heavier objects strike the ground with a greater force

than the lighter objects.

QuestionO If two variables are directly proportional,

thena. An increase in one variable causes a

decrease in the other variableb. The product of the two variables is

constantc. The ratio of the two variable is the

controlled variabled. Neither variable is the controlled variablee. Both variables are constant

CHEMISTRY Composition Structure Properties Reaction

MATTER

MATTER

PURE SUBSTANCE

ELEMENTS

COMPOUNDS

MIXTURE

SOLUTIONS

SUSPENSIONS

COLLOIDS

1. Pure substances, or a simply substance.

OElement – is a substance that cannot be broken down into simpler substances. It has a fixed composition because it contains only one type of atom.

OCompound – is a substance that is made from two or more simpler substances is either elements or other compounds. It always contains two or more elements joined in a fixed proportion.

2. Mixtures, its properties can vary because the composition of a mixture is not fixed.

OHeterogeneous Mixtures – comes from the Greek hetero and genus, meaning “different” and “kind”. The parts of the mixture are noticeably different from one another.

OHomogeneous Mixtures – the substances are so evenly distributed that it is difficult to distinguish one substance in the mixture from one another. It appears to contain only one substance.

Based on the size of its largest particles, a mixture can be

classified as a:OSolutions– when substances dissolve

and form a homogenous mixture. Ex. Sugar & water

OSuspension – is a heterogeneous mixture that separates into layers over time. Ex. Sand & water

OColloid – contains some particles that are intermediate in size between the small particles in a solution and the larger particles in a suspension. Ex. Jellyace, chalk

Properties of Matter

1. Physical Properties2. Chemical Properties

Physical Properties -– is any characteristic of a material that can be observed or measured without changing the composition of the substance in the material.Examples of Physical Propertiesa. Viscosity – the tendency of a liquid to keep from flowing or its

resistance to flowing. The greater the viscosity, the slower the liquid moves such as thick liquid (corn syrup, honey)

b. Conductivity – a material’s ability to allow heat to flow. Ex. Metals

c. Malleability – is the ability of a solid to be hammered without shattering. Ex. Gold and metal

d. Hardness – one way to compare the hardness of two materials is to see which of the materials can scratch the other.

e. Melting and Boiling Points – the temperature at which a substance changes from solid to liquid is its melting point. The temperature at which a substance boils is its boiling point

f. Density – can be used to test the purity of a substance.

Using Physical Properties1. Using properties to identify Materials2. Using properties to choose materials3. Using properties to separate

mixturesOFiltration- is the process that separates

materials based on the size of their particles.

ODistillation – is a process that separates the substances in a solution based on their boiling points

Recognizing Physical Change

OPhysical change occurs when some of the properties of a material change, but the substances in the material remain the same.

Ex. slicing a tomatoCrumpling a piece of paperSlowly heat butter in a pan

Chemical Properties --– any ability to produce a change in the composition of matter. It can be observed only when the substances in a sample of matter are changing into different substances.

Examples of Chemical PropertiesO Flammability – is a material’s ability to burn

in the presence of oxygen.O Reactivity – the property that describes how

readily a substance combines chemically with other substances.

Recognizing Chemical Change

Chemical Change occurs when a substance reacts and forms one or more new substances.

O Three common types of evidence for Chemical change A Change in Color Ex. Banana ripens; match burn Production of a GasEx. when you mix vinegar with baking soda, bubbles of carbon dioxide form immediately Formation of a Precipitate – any solid that forms and

separates from a liquid mixture.Ex. The curds in cottage cheese form when an acid is added to milk

States of Matter

OSolid – materials have definite shape and a definite volume.

OLiquid – materials has a definite volume but not a definite shape.

OGas – material has neither a definite shape nor a definite volume.

ASSESSMENT(Reviewing Content)

QuestionOWhich of these substances is not

an element?a. Waterb. Aluminiumc. Hydrogend. Irone. Nitrogen

QuestionOTap water is a. An elementb. A substancec. A compoundd. A mixturee. A colloid

QuestionOWhich action involves a chemical

changea. Making ice cubesb. Adding sugar to teac. Cutting wrapping paperd. Baking a cake

QuestionOAll pure substancesa. Contain only one type of atomb. Can be broken down into simpler

substancesc. Cannot be broken down into simpler

substanced. Have a fixed compositione. Have a variable composition

QuestionOWhich property can be used to

separate a mixture by distillationa. Melting pointb. Boiling pointc. Densityd. Viscositye. conductivity

QuestionOYou can be certain that a change

is a chemical change ifa. The change cannot be reversedb. New substances formc. Bubbles are producedd. A precipitate formse. There is a color change

QuestionOA beaker containing a black-yellow

powder has a magnet put into it. When the magnet is removed, black particles are stuck to it, leaving a yellow powder behind in the beaker. The black-yellow powder is therefore

a. A mixtureb. A compoundc. An atomd. An element

QuestionOKarl poured some vinegar into a

bottle. He added some baking soda and covered the mouth of the bottle with a balloon. After some time the balloon inflated. What causes the balloon to inflate?

a. Formation of milky substanceb. Formation of precipitatec. Evolution of CO2d. Combination of two substances

QuestionO Refer to the table below:Chemical System

Mixed Substances

Observation Results

A Sugar + water Some sugar articles remain undissolved

B Sugar + hot water

All sugar particles dissolved in hot water

C Egg shells + vinegar

Bubbles moving up to the liquid’s surface

D Milk + lemon juice

White gelatinous solid suspended in liquid

QuestionOYou need 10ml of water in an activity,

if all the given measuring instruments are available, which do you have to use to measure the water.

a. 25 ml beakerb. 50 ml beakerc. 25 ml graduated cylinderd. 50 ml graduated cylinder

QuestionOMixtures that are being stirred

dissolve faster than mixtures that are not stirred. Which of the following factors can explain it?

a. Exposed surface areab. Kind of solventc. Size of the solute particlesd. Temperature due to stirring

QuestionOWhen you see bubbles on the bowl of

soup which had been left on the table for one night, you may infer that:

a. The liquid component of the soup is evaporating

b. Physical change is taking place in the soup

c. The soup is undergoing chemical change

d. Air is dissolved in the soup

PHYSICSForces ENER

GY

MOTION

MOTION

Motion Displacement

Acceleration

Velocity

Distance

Direction of Movement

Speed

Direction of Motion

Change in Speed Changes in Direction Changes in Speed &

Direction

Distance & Displacement

ODistance is the length of the path between two points.

ODisplacement is the direction from the starting point and the length of a straight line from the starting pint to the ending point.

SPEED AND VELOCITYO  Speed is a scalar quantity that refers to

"how fast an object is moving." O Velocity is a vector quantity that refers to

"the rate at which an object changes its position.“

O FORMULA:

Acceleration----can be described as changes in speed, changes in direction, or changes in both. It is a vector.

FORMULA:a= =

FORCEO A force is a push or pull upon an object resulting

from the object's interaction with another object. O Formula: F= mass x accelerationTwo broad categories:1. Contact forces are those types of forces that

result when the two interacting objects are perceived to be physically contacting each other.

2. Action-at-a-distance forces are those types of forces that result even when the two interacting objects are not in physical contact with each other, yet are able to exert a push or pull despite their physical separation

TYPES OF FORCEApplied Force 

An applied force is a force that is applied to an object by a person or another object.Gravity

Force (also known as Weight) 

The force of gravity is the force with which the earth, moon, or other massively large object attracts another object towards itself.

Normal Force 

The normal force is the support force exerted upon an object that is in contact with another stable object.

Friction Force 

A force that opposes the motion of objects that touch as they move past each other.

FRICTIONOFOUR MAIN TYPES OF FRICTION1. Static Friction – is the friction force that

acts on objects that are not moving.2. Sliding Friction – force that opposes the

direction of motion of an object as it slides over a surface.

3. Rolling Friction – force that acts on rolling objects.

4. Fluid Friction – opposes the motion of an object through a fluid

ENERGY----is the ability to do work.FORMS OF ENERGY

MRS CHEN

1. MECHANICAL ENERGYMechanical energy ---- is the energy that is possessed by an object due to its motion or due to its position.OIt can be either 1. kinetic energy - energy of motion2. potential energy - stored energy of

position

2. Radiant energy is the energy of electromagnetic waves. It is a form of energy that can travel through space. 3. Solar Energy is the energy from the sun.4. Chemical Energy – is the energy that results during a chemical reaction.

5. Heat Energy is the energy that comes from heat.6. Nuclear energy refers to the process of using nuclear processes in order to generate heat or electricity.

Newton’s Law of Motion

NEWTON’S FIRST LAW OF MOTION “The state of motion of an object does not change as long as the net force acting on the object is zero.”

NEWTON’S SECOND LAW OF MOTION“The acceleration of an object is equal to the net force acting on it divided by the object’s mass.”

a= =

NEWTON’S THIRD LAW

“Whenever one object exerts a force on a second object exerts an equal and opposite force on the first object.

Energy Conversion----Energy can be converted from one form to another.

Ex. The striking of the match.Chemical Energy Kinetic energy thermal energy

ASSESSMENT(Reviewing Content)

QuestionRody kicks a ball on a level sidewalk. It rolls to stop after sometime because____a. No force is acting on the ballb. Inertia at rest is acting on the

ballc. Gravity pulls the ball downd. Friction slows the ball down

QuestionBikers apply grease to the gears of bicycle to___a. Reduce frictionb. Increase accelerationc. Avoid accidentd. Facilitate easy turn in the

curve

QuestionA taxi and a truck are travelling in the same direction at the same speed. Why would the car accelerate faster than the truck.a. The taxi has less massb. The taxi has less forcec. The taxi has new engined. The taxi has more gasoline

QuestionWhich energy conversion is true for a battery operating toy car?a. Electrical - mechanical -

sound energyb. Chemical – mechanical-soundc. Electrical-mechanical-soundd. Sound-electrical-mechanical

QuestionIf you blow up a balloon, and then release it, the balloon will fly away. This is an illustration of_____a. Newton’s First Lawb. Newton’s second Lawc. Newton’s Third Lawd. None of the above

QuestionYaya Dub placed a thick curtain on the window during summer to minimize the entrance of heat. Which type of heat transfer did she consider?a. Conductionb. Convectionc. Radiationd. Filtration

QuestionA car moves at a constant speed of 25m/s. this means that the car:a. Increase its speed by 25 m/s

every secondb. Decreases its speed by 25 m/s

every secondc. Moves 25 meters every secondd. Doesn’t move

QuestionThe acceleration due to gravity is lower on the moon than on Earth. Which of the following is true about the mass and weight of an astronaut on the Moon’s surface, compared to Earth?a. Mass is less, weight is sameb. Mass is same, weight is lessc. Both mass and weight are the samed. Both mass and weight are less

QuestionAli threw a ball over the fence. What energy did the moving ball have?a. Heat energyb. Potential energyc. Light energyd. Kinetic energy

QuestionA jeep is travelling in a highway at a speed of 100 km/h. suddenly, the driver stepped on the brakes. In what direction will the sitting passengers be thrown when the jeep suddenly stops?a. Forwardb. Backwardc. Sideward leftd. Sideward right

QuestionWhich of the following is not an example of kinetic energy being converted to potential energy?a. Releasing of arrowb. Pulling a plod in the rice fieldc. Releasing of compressed springd. Basketball player jumping for a

rebound

Questionwhich of the following situations illustrates the direct transformation of potential to kinetic?a. A tank is being filled with waterb. An arrow is released from a bowc. The driver steps on the brakes of

his card. The spring of a mechanical toy car

is being turned

QuestionThe following situations show that work is done on an object other than oneself EXCEPT ina. Carrying a 50N laptop to a distance

of 100mb. Going up a flight of stairs with a

backpackc. Lifting a bag of grocery up a jeepd. Pushing a table across the room