Thermodynamics

Thermodynamics

Heat and Thermal Energy

When scientists originally studied thermodynamics, they were really studying heat and thermal energy. Heat can do anything: move from one area to another, get atoms excited, and even increase energy. Did we say energy? That's what heat is. When you increase the heat in a system, you are really increasing the amount of energy in the system. Now that you understand that fact, you can see that the study of thermodynamics is the study of the amount of energy moving in and out of systems. 

Heat of Atoms

Now all of this energy is moving around the world. You need to remember that it all happens on a really small scale. Energy that is transferred is at an atomic level. Atoms and molecules are transmitting these tiny amounts of energy. When heat moves from one area to another, it's because millions of atoms and molecules are working together. Those millions of pieces become the energy flow throughout the entire planet. 

Heat Movement

Heat moves from one system to another because of differences in the temperatures of the systems. If you have two identical systems with equal temperatures, there will be no flow of energy. When you have two systems with different temperatures, the energy will start to flow. Air mass of high pressure forces large numbers of molecules into areas of low pressure. Areas of high temperature give off energy to areas with lower temperature. There is a constant flow of energy throughout the universe. Heat is only one type of that energy. 

Introducing English Verb Tenses

Introducing English Verb Tenses

There are three main verb tenses in English: present, past and future. The present, past and future tenses are divided into four aspects: the simple, progressive, perfect and perfect progressive.

There are 12 major verb tenses that English learners should know.

English has only two ways of forming a tense from the verb alone: the past and the present. For example, we drove and we drive.

To form other verb tenses, you have to add a form of have, be or will in front of the verb. These are called helping, or auxiliary verbs.

Time, culture, and grammar

Verb tenses can be difficult to learn in a foreign language. Different cultures think different ways about time. Chinese, for example, has no grammatical verb tenses. Other languages, like Indonesian, express time only through adverbs — there are no changes to the verb form.

English verb tenses give many details about time and action such as:

Is the action finished?

How long did the action happen?

Was the action repeated?

Did the action happen at a known or unknown time?

Is the action a habit?

Is the action planned or spontaneous?

It is difficult to think about time distinctions that do not exist in your own language. So, it can take many years for English learners to master verb tenses.

Let’s get started. We are going to give examples of all 12 verb tenses using the verb drive.

Simple Tenses

We’ll start with the simple tenses. These are probably the first tenses you learned in English. Simple tenses usually refer to a single action. In general, simple tenses express facts and situations that existed in the past, exist in the present, or will exist in the future.

Simple present: I drive home every day.

Simple past: I drove home yesterday.

Simple future: I will drive home later.

Progressive (Continuous) Tenses

Let’s go on to the progressive tenses. We use progressive tenses to talk about unfinished events. Progressive tenses are also called continuous tenses.

Past progressive: I was driving when you called.

Present progressive: I am driving now.

Future progressive: I will be driving when you call.

Perfect Tenses

Now let’s look at the perfect tenses. Perfect tenses cause the most confusion. To put it simply, they express the idea that one event happens before another event.

There are many tricky exceptions with the perfect tenses, which we will discuss in a future episode. The adverbs never, yet and already are common in perfect tenses.

Present perfect: I have driven that road.

Past perfect: I had already driven that road in the past.

Future perfect: I will have driven 200 miles by tomorrow.

Perfect Progressive Tenses

Finally, let’s look at the perfect progressive tenses. Generally, perfect progressive tenses express duration, or how long? Perfect progressive tenses usually include the adverbs for or since.

Present perfect progressive: I have been driving since this morning.

Past perfect progressive: I had been driving for three hours before I stopped to get gas.

Future perfect progressive: I will have been driving for five hours by the time I arrive.

Don’t worry if you don’t understand everything yet. Here are some recommendations we have for learning verb tenses.

Adverbs are your friends

First, think of adverbs as your friends. Adverbs of time offer valuable clues about the correct verb tense.

Let’s use the adverb ago. Ago is only used in the simple past as in, “I left home three years ago.” The adverb ago is never used in the present perfect. Certain adverbs occur with certain verb tenses.

Keep it simple

English learners sometimes try to impress people by using complex verb tenses. You often have a choice of several verb tenses. When you do, always choose the simplest one. It will be clearer for your listener, and there is less chance of making a mistake.

Practice with questions

Native speakers don’t think consciously about verb tenses. With enough practice, English learners can internalize the verb tense system, too. Instead of worrying about deep time relationships, try using adverbs and your ear to choose the right verb tense.

Often when someone asks a question, you can respond in the same verb tense. We’ll ask a question in each verbtense. Give an answer in the same tense, then listen to our answer.

Ready?

1. Did you get enough sleep last night? (simple past)
Yes, I slept well.

2. Do you shower every day? (simple present)
Yes, I shower every day.

3. Are you going to study tonight? (simple future)
Yes, I’m going to study tonight.

4. What were you doing when I called you last night? (past progressive)
I was eating dinner when you called me last night.

5. What are you doing right now? (present progressive)
I am practicing verb tenses right now.

6. What will you be doing at midnight on New Year’s Eve? (future progressive)
I will be celebrating the New Year with my friends.

7. Had you ever tried skiing before today? (past perfect)
Yes, I had already done it several times before.

8. Have you ever broken the law? (present perfect)
No, I have never broken the law.

9. Will you have gotten married by the time you turn 30? (future perfect)
No, I will not have gotten married by the time I turn 30.

10. How long had you been smoking before you quit? (past perfect progressive)
I had been smoking for two years before I quit.

11. How long have you been waiting for the bus? (present perfect progressive)
I have been waiting for the bus for 20 minutes.

12. How long will you have been working before you retire? (future perfect progressive)
I will have been working for 30 years before I retire.

This is just a basic introduction to verb tenses.

Common Mistakes with English Comparatives and Superlatives

Common Mistakes with English Comparatives and Superlatives

Prepositions in Place Expressions

Prepositions in Place Expressions

Common mistakes in the use of nouns

In this lesson, we will take a look at some common mistakes in the use of nouns.

Incorrect: There is no place on this bus.

Correct: There is no room on this bus.

Incorrect: I am learning a new poetry.

Correct: I am learning a new poem.

Poetry means poems collectively.

Incorrect: He is leaving his service.

Correct: He is leaving his job.

Incorrect: All of my relations are poor.

Correct: All of my relatives are poor.

Incorrect: The clock has struck five hours.

Correct: The clock has struck five.

Incorrect: The boarding is full.

Correct: The boarding house is full.

Incorrect: I saw two females in the store.

Correct: I saw two women in the store.

Incorrect: He enquired about your state of health.

Correct: He enquired about the state of your health.

Incorrect: My English is very weak.

Correct: I am very weak in English.

Incorrect: The weather of Chennai does not suit me.

Correct: The climate of Chennai does not suit me.

Incorrect: Why are you standing in the center of the street?

Correct: Why are you standing in the middle of the street?

Incorrect: I visit them once in a week.

Correct: I visit them once a week.

Incorrect: Her hairs are grey.

Correct: Her hair is grey.

Incorrect: I bought two dozens pencils.

Correct: I bought two dozen pencils.

Incorrect: He took insult at this.

Correct: He took offence at this.

Incorrect: He put your sign here.

Correct: He put your signature here.

Expressing Time in English

Expressing Time in English

Adjectives - Synonyms

What is a synonym?

Synonyms are words or phrases which have the same or nearly the same meaning as other words or phrases in the same language:
The words 'small' and 'little' are synonyms.
Here is a list of synonyms you can use to describe things, feelings or people:

Adjectives	Synonyms
big	large
blank	empty
broad	wide
center	middle
cunning	clever
dangerous	risky
eatable	edible
false	untrue
fertile	fruitful
gay	cheerful
glad	happy
hard	difficult
high	tall
huge	enormous
intelligent	clever
lazy	indolent
little	small
loving	fond
loyal	faithful
mad	crazy
new	modern
nice	kind
noisy	rowdy
old	ancient
oral	verbal
polite	courteous
poor	destitute
quick	rapid/fast
rare	scarce
ready	alert
real	genuine
rich	wealthy
rude	impolite
sad	unhappy
safe	secure
sleepy	drowsy
slim	slender
thin	lean
usual	normal
vacant	empty
weak	feeble
well-known	famous