Physical Science 3rd topic

ASVAB

What is velocity?

the rate an object changes position (Displacement) per unit time.

V=D/T

V= velocity, D=displacement, T= time

What is a vector quantity, And what are examples for motion

fully described by both a magnitude and a direction

both velocity and displacement are a vector they have a arrow on top of them

Time is not a vector

What is momentum

a measure of an objects’s quantity of motion, indicating how difficult it is to stop

what is the formula for momentum

Formula : P=MV

P =Momentum bc the M is already in use by mass,

M= mass

V= Velocity

Remember Mass (X) Velocity you are multiplying

when 2 objects are moving towards each other with opposite directions of momentum what is likely to occur

It will partially or completely cancel out if they collide

what is acceleration?

the rate at which velocity changes it is a vector quantity.

what is the formula for acceleration

Acceleration = change in velocity (divide by) change in time

A= (For change it is a triangle) V / T

What are the key aspects of observing and understanding acceleration?

is visible in a stopped vehicle when the light turns green and the gas pedal is pressed.

It’s indicated by the speedometer needle as the car’s velocity increase to cruising speed .

What is force?

It is the push or pull that cause an object to change its speed or direction of motion

What is weight, and what unit is used to measure force

a force caused by gravity. The unit of force is the newton (N)

Defined as the force needed to accelerate a one-kilogram mass by one meter per second squared.

How does (work) work?

Performed on an object when there is an applied force that is along the same line of movement

what is the formula, where the directions of force and movement are parallel

Work= force X displacement

W=F/d

What are the units of work and energy

is the ( newton-meter) / Joule (J). Energy is also measured in Joules.

Nutritional info on food packages often lists energy in kilojoules (KJ) but mostly know as Calories.

What is power?

the rate a which work is performed or energy is converted.

How can power be calculated using two main formulas

1. Power = Work (Divided by) Time

2. Power = ( force X distance) Divided by time

   P=W/T

What is the main unit of power and its definition?

watt (W). one watt is defined as one joule per second.

How to distinguish between the symbol for work (W) and the unit watt (W) in physics

Its all about content and position in a formula

• Work represents the amount of energy transferred.

it appears as a variable within the equation like P=W/T

• Watt represents the unit of power

It appears after a numerical value like 60W, or 100W

What is newton’s first law of motion

Also known as the Law of Inertia , states that an object at rest will stay at rest, and an object in motion will stay in motion at a constant velocity, unless acted upon by an unbalance forces

An example of an unbalance force - one that keeps objects in motion from staying in motion on earth is

Friction, the force that resists relative motion between 2 bodies in contact

What is newtons second law of motion

When dealing with an object for which all existing forces are not balance, the acceleration of that object , as produced by the net force, is in the same direction as the net force and directly proportional to the magnitude of the net force.

How is newtons second law of motion expressed mathematically

Acceleration=net force /mass

the units for each of these measures must be m/s²,N and kg

a=f/m

What is newton’s law of universal gravitation

All objects in the universe attract each other with an equal force that varies directly as a product of their masses, and inversely as a square of their distance from each other

This force is know as gravity

Fg=Gm1m2/r²

what are sound waves

produced when an object vibrates, disturbing the medium around it,creating an outward ripple in all directions.

when ripples happen in sound waves they

can travel through air, liquids, and solids but they cannot be transmitted through a vacuum, or empty space. sound waves transmitted through air do not travel as fast as those transmitted through water, and those transmitted through water do not travel as fast as those transmitted through metal or wood.

how are sound’s pitch and frequency related

Pitch is directly linked to frequency(vibration rate), measured in hertz(Hz). Humans hear from 20 Hz to 20 kHz.

what is the doppler effect?

Perceived pitch changes when sound sources or listeners move, making sounds higher pitched when approaching and lower when moving away. ex, sirens

What is the electromagnetic spectrum

it encompasses all wavelengths. and frequencies of radiation. Visible light is only a small part of it. it ranges from radio waves to gamma rays.

what is the order of the waves frequencies lowest to highest

1. Radio waves

2. Microwaves

3. Infrared

4. Visible light

5. Ultraviolet

6. X-rays

7. Gamma rays

   to remember

Raging Martians Invaded Venus Using X-ray Guns"

How is visible light related to the electromagnetic spectrum

is a small part ,falling in the middle. It breaks down into different colors based on wave frequency.

How does visible light break down

wavelengths just below visible light’s frequency are called infrared( red has the lowest frequency). Wavelengths just above visible light’s frequency are called ultraviolet (Violet has the highest frequency)

which is faster light or sound

Light, like the electromagnetic spectrum, possess wave properties. Unlike mechanical sound waves, light waves are electromagnetic and can travel through empty space.

Light travels faster than sound waves

The speed of light in a vacuum is approximately 300 million meter per second

However, that the effective speed of light can vary depending on the material the light waves are passing through For example

Light passes more slowly through water or glass than through a vacuum

The ratio by which light is slowed down is called

The refractive index of that medium

For example,The refractive index of a diomond is 2.4 which means that light travels 2.4 times faster when passing throught a vacuum tha when traveling through a diamond

the change in speeds causes light to bend when passing from one medium to another, this bending is called

Refraction, and light bends at a greater angle when the change in the index of refraction is greater

Any wave, including light, that bounces off a flat, smooth barrier follows?

The law of reflection, which states that the angle of incidence is equal to the angle of reflection as measured from a line normal ( at a 90* angle ) to the barrier.

Which in the case of light, this barrier is often a mirror.

Concave mirrors & lenses

Mirrors and lenses can be classified as flat, or they can be curved (concave or convex).

A concave mirror is also known as a converging mirror, this is because , due to the law of reflection, parallel rays of light are all converged upon a point

Convex mirrors are also known as

diverging mirror because it diverges the light waves that strike it.

There are three means by which heat energy may be transferred from one object to another,

Conduction, Convection, and Radiation

Heat energy is always transferred from warmer to cooler environments.

Conduction is

the simplest method of heat transfer, which is accomplished by direct contact

Metals are generally good conductors of heat

Wood , styrofoam, and plastic, are poor for

conductors of heat, which makes them good insulators.

Convection is

transferred through heat by the actual movement of hot particles of a fluid.

Hot air rising from a bonfire is an example of

Convection,

ocean currents and wind are caused by convection movements caused by temperature differences .

Radiation occurs

when electromagnetic waves transmit heat.

The heat we get from the sun travels through space as

Radiation

simple magnets have two poles

A north pole and a south pole

If you try to bring together 2 north poles or 2 south poles for that matter they will?

repel one another , and you can feel their repulsive force

On the other hand if you were to move the north pole of one magnet toward the south pole of another magnet they will

attract each other.

A pure type of matter that cannot be separated into different types of matter by ordinary chemical methods/ all matter is composed of this

Element

The smallest component of an element that still retains the properties of the elements

Atom

A subatomic particle found in the atom’s nucleus that carries a positive electric charge

Proton

A subatomic particle found in the atom’s nucleus that does not have an electric charge and is therefore neutral

Neutron

A subatomic particle that orbits the nucleus of an atom.

Electron, An electron carries a negative charge and has a minuscule mass compared to the other subatomic particles.

The smallest multi-atom particle of an element or compound that can exist in the free state and still retain the characteristics of the element or compound.

Molecule.

In the periodic table, elements are arranged in order of increasing

atomic number

an elements atomic number represents the number of its

protons

The different rows of elements are called

periods

The periodic table has a special name for its columns called a

Group

An atomic mass represents the

average mass of a single atom, elements can vary in their number of neutrons , so individual atoms of an element may be found in a couple of slightly different sizes

The different sizes in an atomic mass are called

Isotopes

A pretty good estimate of atomic mass comes from adding the total number of neutrons and protons together , Each proton and neutron has a mass very close to what’s called an

atomic mass unit (amu)

Unstable elements readily form into

Compounds, with properties very distinct from the elements from which they are composed.

Table salt is called an

Ionic compound

Table sugar is an example of a

covalent compound , which means , among other things, that it does not ionizes when dissolved in water.

An acid is a substance that gives up positively charged hydrogen when

dissolved in water

A base is a

Substance that gives up negatively charged hydroxyl ions

When dissolved in water, basic substances are also referred to as alkaline, bases typically taste bitter.

A pH of a solution is a

number from 0 to 14 that indicates how basic or acidic that solution is

Solutions with a pH less then 7 are

Acidic

Pure water has a pH of 7

Matter may undergo either a

Physical change or a chemical change , the form , size, and shape of matter may be altered in a physical change, but the molecules remain unchanged.

A phase transition is when

matter switches from one state of matter, like solid, liquid, or gas , to another

The liquid state exits at a

higher temperature range relative to the solid state equivalent of the same element or compound.

The gaseous state occurs at a

higher temperature range relative to the previous 2 states of matter

During a chemical reaction, atoms are rearranged into new combinations, resulting in different kinds of molecules, The molecules and atoms that enter the reaction are called

Reactants and the molecules and atoms that result from the reaction are called products.