Praxis 5442 Middle School Science

What are the three main branches of science?

Life Science, Earth Science, Physical Science

Life Science (biology)

the study of all living things

Earth Science

the study of earth and space

Physical Science

the study of matter and energy

What are the basic steps of scientific inquiry?

Ask a question, do background research, make a hypothesis, test your hypothesis, analyze results, draw a conclusion, and share results. Or, if your hypothesis is proven false, make a new hypothesis and start again.

What is a hypothesis?

an educated prediction that can be tested

If your observations do not support your hypothesis, what should you do?

make a new hypothesis based on your observations and begin the process over again

How is evidence used in scientific investigations?

Evidence-observations and data-can either support or oppose a hypothesis.

Compare and contrast a theory and a law

A theory explains why something happens. A law identifies what happens in nature but doesn't necessarily explain why it happens.

What are models, and why are they used in science?

a representation of something. Models are used in science to help us think about things that are difficult to observe in real life.

Give an example of a physical model, a computer model, and a mathematical model.

physical - globes, maps, dioramas

computer - 3D simulations of people or place and simulations of moving weather fronts

mathematical - equaitons (equation of a line) mathematical simulations (business proposals)

Procedure

a step-by-step list of how to carry out an experiment

independent variable

the variable that is changed on purpose in an experiment by the scientist

dependent variable

this factor depends on the independent variable. it is usually the observed outcome of an experiment

constants

factors in an experiment that remain the same

control

a trial where all the variables are held constant

infer

use evidence to draw conclusions about things you may not have directly observed

Describe the difference between precision and accuracy

precision is how consistent and exact a measurement is while accuracy is how close to the actual or true value a measurement is

What does a hypothesis tell you in a lab report?

a hypothesis describes the predictions you were testing

What does a procedure tell you in a lab report?

a procedure is a list of the steps necessary to carry out the experiment

What should you include in a conclusion?

a summary of the results, a discussion of whether or not the data supported the hypothesis, errors, and questions for further investigation

Describe some reasons why you might be critical of scientific findings.

the person or group conducting the experiment is biased, the data seems unreasonable, and/or the results aren't replicable

Describe a situation where you would need to use estimation or round numbers.

any situation where making an exact measurement isn't possible or if you are calculating a number with a repeating decimal

Define bias

a bias is having a special interest that prevents you from being objection or conducting a fair test of your hypothesis

What are the SI units for mass, length, and temperature?

grams, meters, kelvin

What tool would you use to measure the height of your dog?

a meterstick

Where do you look to take a volume reading of a liquid in a graduated cylinder?

the bottom of the meniscus

What is the easiest tool used to measure mass?

an electronic balance

How do you find the volume of a rectangular solid?

you measure the length, width, and height and then multiply all three numbers

Describe the difference between mass and weight.

mass is the amount of matter in a object, and weight is the force applied by a mass

Convert 50 centimeters to kilometers.

0.0005 kilometers

Define volume and list some common volumes measured.

volume is the amount of space something occupies, such as the volume of liquid in a soft drink, the volume of a serving of cereal, or the volume of a backpack

If the boiling point of water in celsius is 100 degrees what is the boiling point in Kelvin?

373.15 degrees K

You place a paper clip in a cup of soda and it sinks. Which is denser - the paper clip or the soda? Would the paper clip most likely have a density of 2.8, 1.0, or 0.3 g/mL?

the paper clip is denser, 2.8g/mL

What is used to heat things with an open flame?

a bunsen burner

What is a safer way to smell a chemical?

Wafting it

what can you use to protect your eyes during labs?

goggles

Don't ______ or drink in a lab

eat

What instrument is like a beaker with a narrower mouth?

a flask

What is the kind of waste that includes living or once living things?

biological waste

A ____________ stand is used in conjunction with a Bunsen burner

ring

What is used to smother small fires or to wrap a person on fire?

a fire blanket

Never leave a heat source______________________.

unattended

What holds the specimen when you use a microscope?

a slide

What is the positively charged particle in an atom?

protons

Describe Thomson's model of an atom.

Thomson thought that electrons and protons were embedded together

If you turn eggs, four, and milk into pancakes, what sort of change have the ingredients undergone?

the ingredients undergo a chemical change - they have transformed into something else with new chemical properties

If you make a smoothie out of a banana, strawberries and yogurt, what sort of changed have the ingredients undergone?

the ingredients have undergone a physical change - they are the same they are just cup up into smaller pieces and blended together

If you burn a piece of paper, is there more or less mass than you started with?

the same, mass in conserved

Name some things that are not matter.

Thoughts, light, a vacuum

In terms of particles and volume, what is the difference between a liquid and a vapor?

they both can flow freely but the particles in a liquid stick together and don't completely separate.

The volume of a liquid is fixed while the volume of a vapor is not.

What happens at the vaporization point (boiling point) of a substance?

at the boiling point, a substance changes from a liquid to a gas

Compare the molecular movements in a solid, vapor, and liquid.

molecules vibrate in a solid, but have fixed positions. molecules in a liquid flow freely but they don't completely separate because they don't have enough energy to completely overcome the attractive forces between the molecules. molecules in a gas move freely and so quickly they can overcome all attractive forces between molecules.

What is viscosity? Which has a higher viscosity: peanut butter or ketchup?

viscosity is the resistance to flow. peanut butter resists flow more

Define vaporization and condensation. Give examples

vaporization is when liquid turns to vapor, like when sweat dries up. condensation is the opposite - when vapor turns to liquid, like when water droplets form on the surface of a glass holding a cold drink

How many known elements are there?

118

Elements are differentiated by their ____________ _____________ because each element has a different number of protons.

atomic numbers

What is the name of a column of elements in the periodic table? What do these elements have in common?

a group is a column of elements in the periodic table. groups of elements have similar physical and chemical properties

What do two or more atoms combine to form?

a molecular compound

What is the atomic mass of an atom?

the atomic mass is the average mass of a typical atom of a particular element. it's also the combined number of protons and neutrons

If the atomic number of an element is 6 and the atomic mass is 15, how many neutrons are present?

Nine - 15-6=9

What is an isotope?

atoms of the same element that have a different number of neutrons

What is a chemical bond?

when atoms share electrons

Why do atoms bond?

so that their electrons can pair up and become more stable

Define substance.

something that can't be broken down into simple parts, and physical changes won't alter its composition

A bowl of beef - barley soup is a ______________________ mixture.

heterogeneous

If the force exerted remains the same, pressure increases as area

decreases

The deeper you of in the ocean, the __________ the pressure gets

higher

What is the concentration of a solution?

the amount of solute contained in a solution

What word described anything that can flow, including water, air, and oil?

fluid

What is the formula for speed?

speed = distance/time

A dolphin swims 56 meters in 8 seconds and a walrus swims 30 meters in 6 seconds. Which is faster?

The dolphin

56/8=7m/s 20/6=5 m/s

Explain why motion is relative. Give an example.

Motion is relative because it is always described in relation to a reference point. For example, we don't see the earth rotating because everything around us is moving with it (including us)

What is required to know the velocity of an object?

the speed and the direction of motion

If you walk around a square block going at the same pace, how many times does your velocity change, and how many times does your speed change?

your velocity changes four times because your are walking in a different direction on each side of the block. you are going at the same pace the entire time, so your speed doesn't change

If a truck driver is driving at 30km/hour and she makes a u-turn, then starts driving at 30km/hour in the opposite direction, did the driver's speed of velocity change after changing direction? why?

the driver's velocity changed because the driver changed directions. the driver's speed did not change

If a bee is flying in a circle at a constant speed, is the bee accelerating?

Yes. acceleration is the change in velocity per unit of time and the bee is constantly changing direction, the bee is also constantly changing velocity and is therefore accelerating

What are the three ways something can accelerate?

When something speeds up, slows down, or changes direction

Describe the difference between a balanced and an unbalanced force.

an unbalanced force has a net force in one direction. balanced forces cancel each other out so there is no action net force.

You and your brother are playing tug-of-war, you pull with a force of 15N, and your brother pulls with a force of 10N. What is the net force?

15N-10N =5N

What is Newton's first law of motion?

objects in motion will remain in motion unless acted on by a net force, and objects at rest will remain at rest unless acted on by a net force

If a 2,000kg car accelerates at a rate of 3m/s2, what is the force the engine applied to the car

f = m x a = (2,000kg) x 3m/s2) = 6,000N

What is Newton's second law of motion?

The acceleration of an object is equal to the net force on a object divided by the mass of the object (a=Fnet/m)

What is the unit of a force, and what is 1 unit equivalent to?

a newton (1N =1kg x m/s2)

What is Newton's third law of motion?

For every action there is an equal and opposite reaction

Explain why the you jump up in the air, you move the the ground doesn't move much.

while the force you apply on earth is equal to th force earth applies on you, accelerations are different because the masses are so different. the force earth exerts of you is enough to send you into the air, but the force you exert on earth is not enough to notice the earth moving away from you

What is the force that attracts masses together?

gravity

Why does a bowling ball have more gravity than a soccer ball?

as mass increases so does the force of gravity

When you push a shopping car, the friction that is opposing the motion is called __________ friction.

rolling

What is centripetal force?

is the force that causes objects to have circular motion

Centripetal force always points toward the _________ of the circular path of motion.

center

Why does a feather drift back and forth as it falls?

air resistance

The force of gravity decreases as the ______________ between masses increases.

distance

In magnetic and electric forces, likes _____________ and opposites attract

repel

When the force of air resistance equals the force of gravity a falling object reaches _____________ velocity.

terminal

What is the name of the upward force exerted on a boat in the water?

buoyancy

What is the buoyant force of a dog that displaces 10lbs of water?

10lbs

When is a person doing work? List some work you do on a daily basis

anytime a person applies a force in the direction of motion, he or she is doing work. jumping up in the air, lifting a back pack, and throwing a ball are all examples of work

When you drop a book, the earth exerts and upward force of 10N on the book. If the book drops 0.5 meters, how much work did the earth do?

work = force x distance

1- newtons x 0.5 meters = 5 joules of work

What is the difference between a simple machine and a compound machine?

a simple machine does work with one motion, and a compound machine combines different machines to produce work