Question

[9/9, 3:34 PM] Vithya JGVV, Science: SHORT ANSWERS
1. Define atmospheric pressure
Ans: The amount of force or weight of the atmospheric air that acts downward on unit surface area of the Earth is known as atmospheric pressure. Thr device used to measure atmospheric pressure is called barometer.

2. What is the value of atmospheric pressure at sea level?
Ans: 76 cm or 760 mm of mercury column.

3. Define: buoyancy or up-thrust
Ans: Buoyancy or up-thrust is an upward force exerted by a fluid that opposes the weight of a body partially or fully immersed object.

4. Name two instruments which help to measure the pressure of a fluid
Ans: (i) barometer (ii) manometer

5. Define: one atmosphere
Ans: The pressure exerted by the mercury column of height 76 cm in the barometer. In SI system,
1 atm = 1,00,000 pascal.
[9/9, 3:47 PM] Vithya JGVV, Science: GIVE REASON
1. Why dams are made stronger and broader at the bottom than at the top?
Ans: This is because the pressure of the water is much greater deeper down and the dam needs to be thick at the bottom so that it is strong enough to withstand this larger pressure.

2. Why do scuba divers wear a special suit while they go into deep sea level?
Ans: As the depth of the sea increases, the pressure increases since pressure increases with depth. The pressure exerted by water deep under the sea is much greater than at the sea level. Hence, the deep sea divers wear special suits which protect them from extreme pressure of water. These suits are called diving suits.​

Answer 1

Answer:

1. The amount of force or weight of the atmospheric air that acts downward on unit surface area of the Earth is known as atmospheric pressure. Thr device used to measure atmospheric pressure is called barometer.
2. 76 cm or 760 mm of mercury column.
3. Buoyancy or up-thrust is an upward force exerted by a fluid that opposes the weight of a body partially or fully immersed object.
4. (i) barometer (ii) manometer
5. The pressure exerted by the mercury column of height 76 cm in the barometer. In SI system,
6. 1 atm = 1,00,000 pascal

REASON:-

1. This is because the pressure of the water is much greater deeper down and the dam needs to be thick at the bottom so that it is strong enough to withstand this larger pressure.
2. As the depth of the sea increases, the pressure increases since pressure increases with depth. The pressure exerted by water deep under the sea is much greater than at the sea level. Hence, the deep sea divers wear special suits which protect them from extreme pressure of water. These suits are called diving suits.

Answer 2

Answer:

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Explanation:

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