A barometer is used to measure which of the following?
- A.Atmospheric pressure
- B.Humidity of the air
- C.Wind speed
- D.Depth of the ocean
Correct answer
Explanation
The correct answer is A, atmospheric pressure. A mercury barometer balances the pressure of the atmosphere against a column of mercury, which stands about 76 centimetres high at sea level. Mercury is chosen because it is very dense, does not wet glass and has a low vapour pressure; a water barometer would need a tube more than ten metres tall. A sudden fall in the barometer reading warns of a storm.
Option B, humidity, is measured by a hygrometer, the wet and dry bulb type being the common one. Option C, wind speed, is measured by an anemometer, usually with rotating cups. Option D, ocean depth, is found with an echo sounder or fathometer, which times a sound pulse reflected from the sea bed. Note also that the aneroid barometer, which uses no liquid, becomes an altimeter when its scale is marked in metres of height.
Read the full article: Gravitation and Pressure: Laws, Formulas and Facts
Practice Questions
View allWhat is the SI unit of pressure?
- A.Newton
- B.Pascal
- C.Joule
- D.Watt
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Pressure is thrust per unit area, so its unit is one newton per square metre, and this unit is named the pascal after Blaise Pascal.
Read the full explanation →The value of acceleration due to gravity on the earth is maximum at which of the following?
- A.The equator
- B.The poles
- C.The centre of the earth
- D.The top of Mount Everest
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The earth is flattened at the poles, so the distance from the centre is least there, and since g varies inversely as the square of that distance, g is largest at the poles.
Read the full explanation →The escape velocity from the surface of the earth is approximately
- A.7.9 kilometres per second
- B.9.8 kilometres per second
- C.11.2 kilometres per second
- D.24 kilometres per second
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Escape velocity is the minimum speed a body must be given so that it leaves the gravitational pull of the planet and never returns.
Read the full explanation →Hydraulic brakes used in automobiles work on which principle?
- A.Archimedes' principle
- B.Pascal's law
- C.Bernoulli's principle
- D.Newton's law of gravitation
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Pascal's law states that pressure applied to an enclosed fluid is transmitted undiminished in every direction to all parts of the fluid and to the walls of the container.
Read the full explanation →The upward force experienced by a body immersed in a fluid is equal to the weight of the fluid displaced by it. This statement is known as
- A.Pascal's law
- B.Archimedes' principle
- C.Hooke's law
- D.Boyle's law
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It states that a body immersed wholly or partly in a fluid experiences an upward buoyant force equal to the weight of the fluid displaced, so the apparent loss in weight of the body equals the weight of the displaced fluid.
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