Tag: pressure exerted by air

Questions Related to pressure exerted by air

A cubical vessel sealed vessel with edge $L$ is placed on a cart, which is moving horizontally with an acceleration `a' as shown iin figure. The cube is filled with an ideal fluid having density $\rho$. Find the gauge pressure at the centre of the cubical vessel.

physics pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

  1. $\dfrac{Ldg}2$

  2. $\dfrac{Ld(g+a)}2$

  3. $\dfrac{Lda}2$

  4. $\dfrac{Ld(g-a)}2$

Show answer
Correct Option: B

State whether given statement is True or False
You find your mass to be $42$kg on a weighing machine. Is your mass more or less than $42$kg?

physics pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

When you weigh your body, an upward buoyant force acts on your body due to the air (a fluid) present around you. As a result, the body gets pushed slightly upwards, causing the weighing machine to show a reading slightly less than the actual value.

State whether true or false:

A sheet of paper falls slower than one that is crumpled into a ball.

physics pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Sheet crumpled into a ball has a small surface area as compared to the similar unfolded sheet. Therefore, unfolded sheet will experience more resistance due to air as compared to the sheet crumpled into a ball, inspite of same force of gravity acting upon them. It is larger resistance of air which slows down the unfolded sheet, and therefore it falls slower as compared to sheet crumpled into a ball.

The boiling point of a liquid can be raised by

physics pressure in fluids and atmospheric pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

  1. Increasing pressure

  2. Decreasing pressure

  3. Increasing the heat supply

  4. Increasing the quantity of the liquid

Show answer
Correct Option: A
Explanation:

When water heats up the molecules move faster and faster and move farther apart, eventually becoming steam. When the pressure on the water is increased,  the molecules are more tightly held. This helps keep them from moving apart so it requires more heat to get them to "break free" and move apart. So, the higher the water pressure the higher the boiling point. 

Cooking is done fast in pressure cooker because

physics pressure in fluids and atmospheric pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

  1. The boiling point of water is lowered

  2. The boiling point of water is increased

  3. More pressure is the cooker cooks the food at 100C

  4. The boiling point remains the same but more steam cooks the food

Show answer
Correct Option: B
Explanation:

In a pressure cooker, as the pressure inside increases with time, the boiling point of water increases and hence is able to cook fast.

When the piston of a pump is pulled up, the pressure inside_____

physics pressure in fluids and atmospheric pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

  1. decreases

  2. increases

  3. remains same

  4. none of the above

Show answer
Correct Option: A
Explanation:

As the piston of pump is pulled up, the pressure inside decrees which leads to unbalance of pressures.

The air pressure inside out body is equal to the ____?

physics pressure in fluids and atmospheric pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

  1. in internal pressure

  2. atmospheric pressure

  3. both a and b

  4. none of the above

Show answer
Correct Option: B
Explanation:

The pressure inside our bodies is equal to the atmospheric pressure and cancels the pressure from outside. we do not get crushed under the atmospheric pressure.

Ink does not spill out of an ink dropper when the atmospheric pressure and ____ pressure are equal.

physics pressure in fluids and atmospheric pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

  1. external

  2. internal

  3. air

  4. vaccuum

Show answer
Correct Option: B
Explanation:

As the pressure inside the dropper, i.e, the internal pressure and the atmospheric pressure become equals,  ink does not spill out.

State whether the following statements are true or false?
(i) the pressure inside our body is equal to the atmospheric pressure
(ii) pressure is inversely proportional to the area.

physics pressure in fluids and atmospheric pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

  1. Both are true

  2. Both are false

  3. (i) True

    (ii) False

  4. (i) False

    (ii) True

Show answer
Correct Option: A
Explanation:

(i) True, because we do not get crushed as the pressure inside and atmospheric pressure becomes equal.

(ii) True, as $pressure=\dfrac{force}{area}$. So, for constant force, $pressure\propto\dfrac{1}{area}$

Height of atmosphere is about ________ $km$.

physics pressure in fluids and atmospheric pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

  1. $3000$

  2. $300$

  3. $30$

  4. $30000$

Show answer
Correct Option: B
Explanation:
Earth is surrounded by an envelope of air which is called atmosphere. The height from Earth's surface upto which it is found is $300kms$