Science 8th Grade Final

Motion

What occurs when an object changes position

Relative Motion

Motion that occurs relative to one’s environment (ex. a person sitting still in a car moving at 55 mph)

Vector Quantity

A measurement/# containing both a magnitude and a direction

Distance

How far an object moves (in length)

Displacement

The distance and direction of an object’s change in position from a starting point (a vector quantity)

Speed

The distance an object travels per unit of time (Derived Unit)

Cannot be a negative value

Meters/Second

SI Unit for speed

S=D/T

Formula for Speed

Average Speed

Total distance traveled / Total time traveled

Instantaneous Speed

Speed measured at one particular point in time

Velocity

Speed with Direction [Formula: V=(Pf-Pi)/T]

Acceleration

A change in velocity

Force

A push or pull that one object can exert on another, causing the object to change in position (move/accelerate)

f=ma

Formula for force (force = mass x acceleration)

kg x m/s² (Newton)

SI unit for force

Balanced Force

when equal forces in opposite directions are applied to an object, resulting in no change in motion as they cancel out

Unbalanced Force

When a force is applied to an object and is not balanced by another force, resulting in a change in motion / acceleration

Net Force

The result (sum) of all forces acting on an object

Inertia

-The tendency of an object to resist a change in motion

-A property of matter (mass)

-The greater the mass of an object, the greater its resistance to a change in motion

Newton’s 1st Law of Motion

The tendancy of an object to resist a change in motion unless acted on by an unbalanced force.

Newton’s 2nd Law of Motion

An object will accelerate in the direction of the net force

Law of Universal Gravitation

An attractive force is always present between any two masses that is greater when the objects are closer together and have more mass

Momentum

a property of an object that is related to how much force is necessary to change its motion. A vector quantity, as it has velocity which has direction

SI Unit for Momentum

kg x m/s

Formula for Momentum

p = m·v

Law of Conservation of Momentum

—Momentum can be transferred from one object to another

—The momentum of an object will not change (it is conserved) unless its mass, velocity, or both, change

—“In the absence of an external force (gravity, friction), the total momentum before the collision is equal to the total momentum after the collision, or is CONSERVED.”

Elastic Collisions

collisions where the objects bounce off of each other or separate.

Inelastic Collisions

—collisions where the objects stick together and move as one. The mass after the collision is equal to the sum of the masses and there is just one final velocity.

Impulse-Momentum Theorum

the impulse (the time over which a force is applied) acting on an object is equal to the change in momentum of the object (its mass x  the change in velocity)

Impulse Equation

Impulse (force x time) = change in momentum (mass x change in velocity)

Force

A push or pull that one object can exert on another, causing the object to change in position (move/accelerate)

f=ma

Formula for force (force = mass x acceleration)

kg x m/s² (Newton)

SI unit for force

Balanced Force

when equal forces in opposite directions are applied to an object, resulting in no change in motion as they cancel out

Unbalanced Force

When a force is applied to an object and is not balanced by another force, resulting in a change in motion / acceleration

Net Force

The result (sum) of all forces acting on an object

Inertia

-The tendency of an object to resist a change in motion

-A property of matter (mass)

-The greater the mass of an object, the greater its resistance to a change in motion

Newton’s 1st Law of Motion

An object will resist a change in motion unless acted on by an unbalanced force.

Newton’s 2nd Law of Motion

An object will accelerate in the direction of the net force

Law of Universal Gravitation

An attractive force is present between any two masses that is greater when the objects are closer together and have more mass

Newton’s 3rd Law

Every action has an equal opposite reaction

Friction

The force between two surfaces that are touching one another

Factors Affecting Friction

The objects’ masses and the materials touching each other

Fluid Friction

The friction of an object moving through a fluid

Static Friction

The friction between two surfaces that are not moving past each other - the greatest type of friction due to needing to overcome it to begin motion

Rolling Friction

The friction between a rolling object and the surface it rolls on - the least amount of friction because each point of the wheel does not make contact with the surface it rolls on for long enough for the surfaces to interlock

Centripetal Force

A force directed toward the center of a circle for an object traveling in a circular path

Energy

the ability to do work or cause change

Kinetic Energy

The energy of motion (KE)

Potential Energy

Stored energy (PE)

Joules

SI Unit of measurement for energy and work (kg·m²/s²)

Kinetic Energy Formula

KE=1/2m·v²

Gravitational Potential Energy

(GPE) Energy stored in objects above the Earth’s surface

Gravitational Potential Energy Formula

GPE=m·9.8m/s²·h

Law of Conservation of Energy / The 1st Law of Thermodynamics

Energy cannot be created or destroyed, it simply changes from one form to another

Mechanical Energy

the energy of a system of moving parts It is found in a system of objects that are moving or have the potential to move

Chemical Energy

energy that is stored in the bonds between the atoms of compounds. If the bonds are broken, the energy is released and can be converted to other forms of energy.

Electrical Energy

the energy of moving electrons. Electrons flow through wires to create electric current.

Electromagnetic Energy

energy that travels through space as electrical and magnetic waves. types include radio waves, microwaves, X rays, and gamma rays. Also known as radiant or light energy

Thermal Energy

The sum of kinetic and potential energy in an object. (the energy of moving atoms of matter.) All matter has this energy because atoms of all matter are constantly moving. An object with more mass has more of this energy than an object with less mass because it has more atoms.

Sound Energy

a form of mechanical energy that starts with a vibration in matter. The vibrations pass to surrounding particles of matter and then from one particle to another in waves. Sound waves can travel through air, water, and other substances, but not through empty space.

Nuclear Energy

energy that is stored in the nuclei of atoms because of the strong forces that hold the nucleus together. The energy can be released in nuclear power plants by splitting nuclei apart. It is also released when unstable (radioactive) nuclei break down, or decay.

Work

When a force is exerted on an object and the object moves in the direction of the force

Work Formula

Work = force (kg·m/s²) · distance (m)

Power

The rate at which work gets done

Watt

SI unit for power (joules/sec)

Watt Formula

Work/time

Vacuum

A space that has no matter

Seismic Energy

released when earthquakes occur, transferred by waves moving through the ground

Energy Transformation

When energy changes form

FIssion

When big atoms are slit into smaller ones, releasing energy that can cause a chain reaction. This occurs on the sun and on earth

Fusion

When small atoms are merged into larger ones, releasing safe clean energy. This occurs on the sun

Waves

Rhythmic disturbances that carry energy through matter or space

Medium

Material (matter) through which a wave transfers energy. Electromagnetic waves can travel without a medium (in a vacuum)!

Crest

Top of wave

Trough

Bottom of wave

Amplitude

How far from the midline the crest or trough of a wave is

Wavelength

The length of one wave

Frequency

the # of waves that can pass a point in one second. More of these = shorter wavelength = more energy = can penetrate more matter

300,00 km/s

Speed of light in a vacuum

Length

The distance between two points, also called height, distance, or width

Mass

The amount of matter in an object

Volume

The amount of space an object takes up

Storin’ and Pourin’

Purpose of a Beaker

Measuring the Volume of Liquid

Purpose of a Graduated Cylinder

Derived Unit

2 or more simple units combined

Density

Mass over Volume

Kelvin

SI unit for Temperature

Second

SI unit for time

Meter

SI unit for length

Gram

SI unit for mass

Liter

SI unit for volume

Meniscus

The middle of the curve at the top of a liquid in a graduated cylinder

100 degrees

Temperature at which water boils (Celcius)

0 degrees

Temperature at which water freezes (Celcius)

0 degrees

Absolute Zero (Kelvin)

Accuracy

Getting close to the right answer

Presicion

Consistently getting a specific answer

Line Graphs

Can show relationships where the DV changes due to changes in the IV, often shows changes over time

X axis

Horizontal axis, always the IV