Motion Glossary and Terms

                         Motion Glossary and Terms

 Acceleration - Acceleration is the measurement of the change in an object's velocity. It is equal to the change in velocity over the change in time. Acceleration is a vector. 

Collision - A collision in physics occurs when any two objects bump into each other. 

Displacement - In physics, displacement refers to an object's overall change in position. It is a vector quantity. 

Energy - Energy is the ability to do work. The standard unit of measure for energy is the joule. 

First law of motion - The first law of motion states that any object in motion will continue to move in the same direction and speed unless external forces act on it. 

Force - Force is the measurement of a push or pull on an object. Force is a vector measured in newtons. 

Friction - Friction is the resistance of motion when one object rubs against another. It is a force and is measured in newtons. 

Gravity - Gravity is a force caused when the mass of physical bodies attract each other. On Earth gravity pulls at objects with an acceleration of 9.8 m/s². 

Impulse - An impulse is a change in momentum. 

Joule - The joule is the standard unit of measure for energy and work. 

Kinetic energy - Kinetic energy is the energy an object has due to its motion. It is a scalar quantity calculated using the formula KE = ½ * m * v², where m = mass and v = velocity. 

Mass - Mass is a measurement of how much matter is in an object. It is usually measured in kilograms. 

Momentum - Momentum is a measurement of mass in motion. Momentum is equal to the mass times the velocity of an object. It is a vector measured in newton-seconds. 

Newton - The newton is the standard unit of measure for force. 

Pascal - The pascal is the standard unit of measure for pressure. 

Potential energy - Potential energy is the energy stored by an object due to its state or position. It is measured in joules. 

Power - Power is a measurement of the rate at which energy is used. Power is calculated by dividing work over time. The standard unit for power is the watt. 

Pressure - Pressure is the force over a given area. Pressure is measured in pascals. 

Scalar - A scalar is a measurement that only measures the magnitude. Unlike a vector, a scalar does not have direction. 

Second law of motion - The second law of motion states that the greater the mass of an object, the more force it will take to accelerate the object. 

Simple machine - A simple machine is a basic mechanical device for applying a force and doing work. Some examples of simple machines include the lever, pulley, inclined plane, wedge, and screw.

Speed - Speed is the measurement of how fast on object moves relative to a reference point. It is a scalar quantity measured by distance over time. 

Third law of motion - The third law of motion states that for every action there is an equal and opposite reaction. 

Vector - A vector is a quantity that has both a magnitude and a direction. 

Velocity - Velocity is the rate of change in an object's position. Velocity is a vector quantity. The magnitude of velocity is the object's speed. 

Watt - The watt is the standard unit of measure for power. 

Weight - Weight is the force of gravity on an object. In physics, weight is measured in newtons. 

Work - Work occurs in physics when a force acts on an object to move it some distance. Work is equal to the force times the distance and is measured in joules. 

What is Radiant Energy?

What is Radiant Energy?

What's the first thing you think of when you think of the sun; warmth, light, sunburns, blue skies, growing plants? The energy from the sun is an important factor for life on earth. The heat and light we associate with the sun are forms of radiant energy. Energy is the ability to do work, and radiation is energy that travels in waves. There are other forms of radiant energy besides heat and light. All the different forms of radiant energy make up the -electromagnetic spectrum.

What is the Electromagnetic Spectrum?

Have you observed a rainbow after it rains? All those colors of light are a small part of the electromagnetic spectrum and the only part we can see. We see the light from the sun, but don't necessarily see the heat. Heat is known as infrared light. Some of the other forms of radiant energy you may know are ultraviolet light, x-rays, gamma rays, microwaves and radio waves. All these forms of radiant energy travel in waves at the same speed but each forms' waves are different in size. Radio waves are very large, low energy waves traveling through the air (though we can't see them) in comparison to x-rays that are small, high energy waves.

A rainbow is radiant energy we can see

How is it used?

Sir William Crookes discovered the electromagnetic spectrum in 1885. That's over 130 years ago! Scientists are still studying and learning about radiant energy, how it works and how we can use it. Radiant energy is an important part of our world. Telecommunications like wireless networks, remote controls, heating, lighting, and branches of the medical field such as laser surgery and radiation therapy are just a few examples of our current technological uses of radiant energy.

What is Physics? |

What is Physics? |

Must and Have to

What's the difference between must and have to?

Must and have to are modal verbs in English. This page will guide you to the proper use of these modals.

Must

1. We use must to make a logical deduction based on evidence. It indicates that the speaker is certain about something:
Examples:

• It has rained all day, it must be very wet outside.
• The weather is fantastic in California. It must a lot fun to live there.

2. Must is also used to express a strong obligation.
Examples:

• Students must arrive in class on time.
• You must stop when the traffic lights are red.
• I must go to bed.

Have to

Like must, have to is used to express strong obligation, but when we use have to there is usually a sense of external obligation. Some external circumstance makes the obligation necessary.
Examples:

• I have to send an urgent email.
• I have to take this book back to the library.

The Map of Physics

Nouns and gender

Most English nouns do not have grammatical gender. Nouns referring to people do not have separate forms for men (male form) and women (female form). However, some nouns traditionally had different forms. Nowadays, people usually prefer more neutral forms.

male form	female form	neutral form
actor	actress	actor
chairman	chairwoman	chair or chairperson
headmaster	headmistress	headteacher or head
host	hostess	(social) host (on an aircraft) cabin attendant
policeman	policewoman	police officer
steward	stewardess	(on an aircraft) cabin attendant
waiter	waitress	waiter

 

Traditional work-roles

Some jobs were normally done by men in the past, and their names had no form for women (e.g. fireman, fisherman). Some were normally done by women, and their names had no form for men (e.g. nurses and secretaries were almost always women). Nowadays, fire-fighter is preferred to fireman, and nurse is preferred for both sexes instead of male nurse for a man. Personal assistant (or PA) is often used instead of secretary. The neutral words are more ‘politically correct’ (not likely to offend anyone):

Two fire-fighters were injured in a blaze at an electronics factory yesterday.

My brother’s a nurse in the local hospital.

Animal names

Some animal names have male and female forms. Very often, one of the names acts as a neutral term, even if we know the sex of the animal.

male	female	neutral
bull	cow	cow
dog	bitch	dog
drake	duck	duck

Prepositions

Prepositions

We commonly use prepositions to show a relationship in space or time or a logical relationship between two or more people, places or things. Prepositions are most commonly followed by a noun phrase or pronoun (underlined):

The last time I saw him he was walking down the road.

I’ll meet you in the cafe opposite the cinema.

It was difficult to sleep during the flight.

It was the worst storm since the 1980s.

Give that to me.

There are over 100 prepositions in English. The most common single-word prepositions are:

about	beside	near	to
above	between	of	towards
across	beyond	off	under
after	by	on	underneath
against	despite	onto	unlike
along	down	opposite	until
among	during	out	up
around	except	outside	upon
as	for	over	via
at	from	past	with
before	in	round	within
behind	inside	since	without
below	into	than
beneath	like	through

Although most prepositions are single words, some pairs and groups of words operate like single prepositions:

They were unable to attend because of the bad weather in Ireland.

Jack’ll be playing in the team in place of me.

In addition to getting a large fine, both brothers were put in prison for three months.

I always get nervous when I have to speak in front of an audience.

We estimate that there’ll be up to 10,000 people at the concert.

The most common prepositions that consist of groups of words are:

ahead of	except for	instead of	owing to
apart from	in addition to	near to	such as
as for	in front of	on account of	thanks to
as well as	in place of	on top of	up to
because of	in spite of	out of
due to	inside of	outside of

Prepositions or conjunctions?

Some words which are prepositions also function as conjunctions. When we use a preposition that is followed by a clause, it is functioning as a conjunction; when we use a preposition that is followed by a noun phrase, it stays as a preposition. Among the most common are after, as, before, since, until:

After I’d met him last night, I texted his sister at once. (conjunction)

After the meeting last night, I texted his sister at once. (preposition)

We’ll just have to wait until they decide what to do. (conjunction)

Okay, we’ll wait here until six o’clock. (preposition)

Prepositions or adverbs?

Several words which are prepositions also belong to the word class of adverbs. These include: about, across, around, before, beyond, in, inside, near, opposite, outside, past, round, through, under, up, within:

There were lots of people waiting for a taxi outside the club. (preposition)

A:

Where’s your cat?

B:

She’s outside. (adverb)

The gallery is opposite the Natural History Museum. (preposition)

A:

Can you tell me where the bus station is?

B:

It’s over there, just opposite. (adverb)