• The concept of bernoulli's principle - class-VII
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The concept of bernoulli's principle - class-VII

Description: the concept of bernoulli's principle
Number of Questions: 22
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Tags: physics properties of natural resources air, winds and cyclones chemistry winds, storms and cyclones statics and dynamics of fluid (liquid and gas) natural disasters: winds, storms and cyclones
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What happens when cold air meets warm air 

physics winds, storms and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure

  1. it forms front

  2. it creats a tomado

  3. it creates a mansoon

  4. none of these

Show answer
Correct Option: A

When a fluid is heated, it expands and becomes

physics winds, storms and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure wind and rain uneven heating of earth

  1. lighter

  2. heavier

  3. no change

  4. none of these

Show answer
Correct Option: A
Explanation:
As on heating the air expands and occupies more space. When the same thing occupies more space, it becomes lighter. The warm air is, therefore, lighter than the cold.

Iron, hydrogen peroxide and carbon dioxide. When same amount heat is supplied to these three substances, which expands most?

physics winds, storms and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure wind and rain uneven heating of earth

  1. Hydrogen peroxide

  2. Carbon dioxide

  3. Iron

  4. All of these

Show answer
Correct Option: B
Explanation:

Carbon dioxide being a gas expands the most. 

Which of the following will rise the highest?

physics winds, storms and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure wind and rain uneven heating of earth

  1. Air at 10$^o$C

  2. Air at 40$^o$C

  3. Air at 20$^o$C

  4. Air at -5$^o$C

Show answer
Correct Option: B
Explanation:

As the temperature of air rises, it becomes lighter and moves at a faster rate and thus it rises higher in the atmosphere.

Thus air at $40^oC$ will rise the highest in the atmosphere.

Why do two balloons come closer when we blow in the space between them ?

physics air, winds and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure wind and rain uneven heating of earth

  1. Greater pressure inside the balloons than the reduced pressure in between them drives the balloons towards one another.

  2. Blowing air in between increases the pressure in between the balloons pulls them closer.

  3. The gravitational force pulls the two balloons closer.

  4. None of the above.

Show answer
Correct Option: A
Explanation:
When we blow between two balloons, they come closer because the pressure between the balloon decreases. The pressure inside the balloon would then push them towards each other.

Which of the following is/are true?

physics air, winds and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure wind and rain uneven heating of earth

  1. The wind blows because of differences in air pressure from one location to another

  2. Wind blows from areas of high pressure toward areas of low pressure

  3. If the high pressure area is very close to the low pressure area, or if the pressure difference is very great, the wind can blow very fast

  4. All of the above

Show answer
Correct Option: D
Explanation:
Wind flowing is the result of pressure difference in air between the two regions. Winds flows from the region of higher pressure to the region of lower pressure. Greater is the pressure difference, greater is the speed of the wing flowing and vice-versa.
Thus all the statemements are true, so option D is correct.

Which of the following is/are correct?

physics air, winds and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure wind and rain uneven heating of earth

  1. Warm air rises

  2. Cold air rises

  3. Cold air sink

  4. Both A and B

Show answer
Correct Option: A,C
Explanation:

Warmer air becomes lighter and so it rises whereas cold air sinks.

Which of the following is/are NOT true?

physics air, winds and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure wind and rain uneven heating of earth

  1. Temperature also makes changes in air pressure

  2. In cold air, the molecules are more closely packed together than in warm air, so cold air is more dense than warm air

  3. Air pressure depends on the density of the air, or how close together its molecules are

  4. None of the above

Show answer
Correct Option: D
Explanation:
Air pressure is dependent on the temperature of air. More is the temperature, more is the air pressure and vice-versa. In cold air, the temperature is low and so the molecules of air have less kinetic energy. Due to this, the molecules are more closely packed together than in warmer air and so cold air is more dense than warm air. This also suggests that lesser is the temperature of air, more is the density of air and less is the air pressure. Hence, air pressure also depends on the density of the air.
So, all the statements are true.

____ pressure indicates sinking air where clouds cannot form. ____ pressure indicates rising air, which allows clouds to form, bringing rain or snow. Fill in the blank.

physics air, winds and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure wind and rain uneven heating of earth

  1. High, high

  2. High, low

  3. Low , low

  4. Low, high

Show answer
Correct Option: B
Explanation:

High pressure indicates sinking air where clouds cannot form. Low pressure indicates rising air, which allows clouds to form, bringing rain or snow.

When a vehicle travels very fast, a region of ______ is created temporarily just behind it.

chemistry air, winds and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure variations in atmospheric pressure wind and rain uneven heating of earth

  1. High pressure

  2. Low pressure

  3. High density

  4. Cyclone

Show answer
Correct Option: B
Explanation:
When a vehicle moves very fast, a low pressure is produced temporarily and the wind nearby rushes in to fill its place.

Which of the following principle shows that if you increase air speed its pressure will decrease?

chemistry air, winds and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure variations in atmospheric pressure wind and rain uneven heating of earth

  1. Darwin principle

  2. Einstein principle

  3. Bohr principle

  4. Bernoulli's principle

Show answer
Correct Option: D
Explanation:
According to Bernoulli's principle, Fast moving air equals low air pressure while slow moving air equals high air pressure.
 Bernoulli's principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in pressure. The same is applicable in case of gases also.

Increase in air speed is associated with ______________ .

chemistry air, winds and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure variations in atmospheric pressure wind and rain uneven heating of earth

  1. increasein air pressure

  2. decrease in air pressure

  3. increase in air temperature

  4. decrease in air temperature

Show answer
Correct Option: B
Explanation:
The increased wind speed is accompanied by a reduced air pressure.

A piece of paper is kept on the table.  You have to lift it from the table by blowing high-speed air over it. In which direction will you blow the air?

chemistry air, winds and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure variations in atmospheric pressure wind and rain uneven heating of earth

  1. Sideways

  2. In the upward direction

  3. In the downward direction

  4. In the upward direction below the table

Show answer
Correct Option: A
Explanation:
In order to lift the paper up from the table we need to blow air in sideways.

Two pieces of papers are held parallel. Air is blown with a high speed in between them. Which of the following phenomena will be observed?

chemistry air, winds and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure variations in atmospheric pressure wind and rain uneven heating of earth

  1. The papers will move away from each other.

  2. The papers will move towards each other.

  3. The papers will stay at their position.

  4. The papers will catch fire due to increase in air temperature.

Show answer
Correct Option: B
Explanation:
It seems amazing that the two sheets of paper move closer together, the pressure is reduced where the air is moving quickly. This is called the Bernoulli principle. 

Why is warm air lighter than cold air?

physics air, winds and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure wind and rain uneven heating of earth

  1. Due to heating, the pressure of air increases and air with higher pressure is lighter than air with lower pressure.

  2. Due to heating, the pressure of air decreases and air with lower pressure is lighter than air with higher pressure.

  3. Due to heating, air expands. When same mass occupies more volume it becomes lighter.

  4. Due to heating, air contracts. When same mass occupies less volume it becomes lighter.

Show answer
Correct Option: C
Explanation:
Warm air lighter than cold air because on heating the air expands and occupies more space. When the same thing occupies more space, it becomes lighter.

The air just above the flame of burning candle will ____________.

physics air, winds and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure wind and rain uneven heating of earth

  1. Rise up

  2. Moves down

  3. Moves sideways

  4. It will not move in any direction.

Show answer
Correct Option: A
Explanation:
The burning candle releases hot air, and we know hot air rises up.

The warm air ___, and the cooler air from the regions in the 030 degrees latitude belt on either side of the ____moves in.

physics air, winds and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure wind and rain uneven heating of earth

  1. moves downwards, equator

  2. rises, pole

  3. rises, equator

  4. moves downwards, pole

Show answer
Correct Option: C
Explanation:
The warm air at the latitudes rises up and the cold wind from the polar regions rushes in, to take its place.

Choose the correct options (one or more) 
At the equator, the air is _____ than that at latitudes about 30 degrees.

physics air, winds and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure wind and rain uneven heating of earth

  1. warmer

  2. colder

  3. heavier

  4. lighter

Show answer
Correct Option: A,D
Explanation:
As we know regions close to the equator get maximum heat from the Sun. Hence, the air in these regions gets warm and warm air is lighter and rises up.

Choose the correct options (one or more)
At the poles, the air is _____ than that at latitudes about 60 degrees.

physics air, winds and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure wind and rain uneven heating of earth

  1. warmer

  2. colder

  3. lighter

  4. Heavier

Show answer
Correct Option: B,D
Explanation:
At the poles, the air is colder than that at latitudes about 60 degrees and cold air is heavier than warm air.

State whether true or false :
"Moisture" refers to the presence of liquid generally water in very trace amounts.

physics air, winds and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure wind and rain uneven heating of earth

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

The correct answer is option(A).

Moisture is the presence of a liquid, especially water, often in trace amounts.

"Water vapor" refers to :

physics air, winds and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure wind and rain uneven heating of earth

  1. liquid state of water

  2. solid state of water

  3. invisible gaseous state of water

  4. None of these

Show answer
Correct Option: C
Explanation:
Water vapour or aqueous vapour is the gaseous phase of water.

The continuous spectrum is obtained when the incandescent substance is?

physics air, winds and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure wind and rain uneven heating of earth

  1. In state of atomic vapour

  2. In solid state

  3. In state of molecular vapour

  4. None of these

Show answer
Correct Option: B
Explanation:

An incandescent light bulb produces a continuous spectrum because the source of the light is a metal filament (i.e. solid).

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