8th Grade Science Final Exam: Energy, Waves, Light, and Matter

What is work?

the transfer of energy that occurs when a force makes an object move in the direction of the force.

What is efficiency?

the ratio of output work to input work.

What is the law of conservation of energy?

energy can be transformed from one form to another, but it cannot be created or destroyed.

What is energy?

the ability to cause change.

What are sound waves?

mechanical, longitudinal waves that travel through matter.

What matter can sound waves travel through?

solids, liquids, and gases.

What causes sound waves?

Vibrations .

What is pitch?

the perception of how high or low a sound seems.

What organ do humans use to produce sound of different pitches?

Humans use vocal cords to produce sounds

What is one function of the inner ear?

converts sound vibrations into nerve signals that are sent to the brain.

What type of sonar do some animals like bats use to navigate and catch prey?

Some animals use echolocation to navigate and catch prey.

Which types of waves travel through matter?

Mechanical waves like sound waves and electromagnetic waves like light travel through matter.

Which type of wave can travel through a vacuum (empty space)?

An electromagnetic wave like light .

What type of material allows light to pass through and form a clear image?

Transparent material allows light to pass through and form a clear image.

What type of material allows most light to pass through?

Translucent material allows most of the light to pass through.

What type of material does not allow light to pass through?

Opaque material does not allow light to pass through.

What is refraction of light?

when light changes direction because it travels through different materials.

When does reflection of light occur?

occurs when light waves bounce off a surface.

What are the three types of mirrors?

plane (flat), concave (curved inward), and convex (curved outward).

How does a lens affect the transmission of light?

causes light to change direction.

What is the function of the eye's cornea?

changes the direction of light waves as they enter the eye.

What is the function of the eye's iris?

relaxes and contracts to control the amount of light entering the eye.

What is the function of the eye's retina?

where an image forms and nerve signals are produced.

What is the function of the eye's rod cells and cone cells?

help us see in dim light while, help us to see color.

What is potential energy?

stored energy based on mass and height from the ground.

What is kinetic energy?

the energy an object has because of its motion.

What is the freezing point of water in Celsius and Fahrenheit?

0 degrees and 32 degrees

What is the boiling point of water in Celsius and Fahrenheit?

100 degrees and 212 degrees

What is the freezing point and boiling point of water on the Kelvin scale? and what does absolute zero mean?

The freezing point of water is about 273 K and the boiling point is about 373 K. Absolute zero is the theoretical value at which all molecules stop moving

How is thermal energy transferred?

by radiation, convection, and conduction.

In which states of matter does convection occur?

in liquids and gases.

Do electrons move more easily through a thermal conductor or a thermal insulator?

Electrons move more easily through a thermal conductor.

What is thermal expansion?

an increase in volume of a material when the temperature increases.

What is thermal contraction?

a decrease in volume of a material when the temperature decreases.

What are the four states of matter?

solid, liquid, gas, and plasma.

What are some factors that determine the state of matter?

pressure, temperature, particle motion, and particle forces.

What is viscosity?

the measure of a liquid's resistance to flow.

Contrst the movement of particles during freezing and melting?

When Freezing, The particles slow down and become closer together while duriong melting kintetic energy increase and particles move farther apart

What is pressure?

the amount of force applied per unit of area.

What does Boyle's Law state?

when temperature is constant, the pressure of a gas increases when the volume decreases.

What does Charles' Law state?

when pressure is constant, the volume of a gas increases when the temperature increases.

Particles that are frather apart have _______ potential energy

Greater

What is a chemical bond that forms when two atoms share valence electrons called?

a covalent bond.

What is a valence electron?

one of the outermost electrons of an atom that forms chemical bonds.

The closer the nuclues, the ______ and electron's energy level

Lower

What does the nucleus of an atom contain?

protons and neutrons.

What are common properties of covalent compounds?

low melting and boiling points and are poor conductors.

How can molecules be modeled?

h a dot diagram, structural formula, ball and stick model, or space filling model.

What does H₂O represent?

two hydrogen atoms and one oxygen atom forming a molecule of water.

Why are noble gases stable?

because all valence electrons are paired.