Class 10th

In Indirect Speech, pronouns change according to the perspective of the speaker and listener.

Direct: Pinky said to me, "I will help you."

Indirect: Pinky told me that she would help me.

Here, 'I' becomes 'she', and 'you' becomes 'me'.

Sentences with Direct speech reports the exact words of the speaker, as spoken by him/her, within quotation marks, while indirect sentences conveys the meaning of the message without quotation marks.

For example:

Direct: She said, "I am happy."

Indirect: She said that she was happy.

Through isotropy, we can say it enables equal distribution of velocity components in all directions. This allows us to replace directional velocity terms with a fraction of the total velocity squared. That basically simplifies the pressure formula to involve only rms speed.

This is because pressure is a result of how momentum transfers during collisions. We also know that momentum depends on velocity. The derivation shows that pressure is proportional to the average of squared velocities. That we know from the root-mean-square (rms) speed.

Surprisingly, the viscosity of a dilute gas behaves exactly opposite to what you might expect for liquids. Liquid viscosity generally decreases as temperature is lowered. The viscosity of a dilute gas increases as and when you raise its temperature. This counter-intuitive behaviour was clearly established experimentally and is explained by the kinetic theory.

It's because gas molecules constantly move around at super high speeds. They randomly bump into each other constantly. Gravity does pull on them. The pulling effect is not much, however. When we consider the distance from the floor to the ceiling, gravity's pull is overcome by the molecular kinetic energy. So they just spread out and move from one place to another. They can't settle down. 

Check out some good books for prepositional phrases:

Here are three examples of prepositional phrases:

• I found the sock under the bed.
• She stood by the river and wept.
• Jane walked slowly towards the house.

A prepositional phrase is a group of words that begins with a preposition (e.g. as in, on, under, with, etc.) and ends with its object. The object is often accompanied by modifiers that describe it.

Example: She stood under the shade.