Practice MCQ Questions and answers on Physics-GK

21

The atmospheric air is held to the Earth by :

A) Gravity B) Winds C) Clouds D) Rotation of the Earth

Discuss

Answer & Solution

Answer: Option A

Solution:

Surface gravity, the force that holds down an atmosphere, differs significantly among the planets.

22

The pressure of a fluid varies with depth h as P = PQ+pgh, where p is the fluid density. This expression is associated with

A) Pascal's law B) Newton's law C) Bernoulli's principle D) Archimedes' principle

Discuss

Answer & Solution

Answer: Option A

Solution:

The pressure of a fluid varies with depth h as P = PQ+pgh, where p is the fluid density. This expression is associated with Pascal's law.

23

A parachute descends slowly whereas a stone dropped from the same height falls rapidly, because

A) Stone is heavier than parachute B) Special mechanisms are present in parachute C) A parachute has a larger surface area and air resistance is more D) None of these

Discuss

Answer & Solution

Answer: Option C

Solution:

Gravity is pulling the man down while friction with the air slows him down. With the parachute out it adds more friction slowing him down because air resistance works against the very large surface area of the parachute. A free falling skydiver that has not yet opened his parachute can make his downward speed vary between about 110 mph and 225 mph using air resistance. A spread eagled position presents the maximum area, and we fall the slowest.

24

Why does bleeding occur through the nose in high mountainous regions ?

A) The pressure of blood in capillaries is greater than the outside pressure B) The pressure at high altitudes is greater than that on the plains C) The blood pressure of a person increases at high altitudes D) The blood pressure fluctuates and finally decreases drastically

Discuss

Answer & Solution

Answer: Option C

Solution:

Nosebleeds can be caused by being up in a very high altitude. As you climb higher, the amount of oxygen in the air decreases. This makes the air thinner and dryer, which can in turn cause the inside of your nose to crack and bleed.

25

Which of the following instruments is used to measure humidity ?

A) Kata Thermometer B) Anemometer C) Sling Psychrometer D) Clinical Thermometer

Discuss

Answer & Solution

Answer: Option C

Solution:

A hygrometer is an instrument used to measure relative humidity. Humidity is the measure of the amount of moisture in the air. A psychrometer is an example of a hygrometer.

26

Anemometer is an instrument meant for measuring ________

A) Velocity B) Air masses C) Wind speed D) Temperature

Discuss

Answer & Solution

Answer: Option C

Solution:

An anemometer is an instrument that measures wind speed and wind pressure. Anemometers are important tools for meteorologists, who study weather patterns.

27

A fountain pen works on the principle of

A) Flow of liquids from higher to lower potential B) Capillary action C) Bernoulli's principle D) Viscosity of liquids

Discuss

Answer & Solution

Answer: Option B

Solution:

A fountain pen is a nib pen that, unlike its predecessor, the dip pen, contains an internal reservoir of liquid ink. The pen draws ink from the reservoir through a feed to the nib and deposits it on paper via a combination of gravity and capillary action.

28

A barometer is kept inside a bell jar. Air is slowly pumped out of the jar.

A) The mercury level starts rising B) The mercury level starts falling C) The mercury level does not change D) The bell jar breaks up

Discuss

Answer & Solution

Answer: Option A

Solution:

As the pump removes the air from the bell jar the pressure obviously reduces around the barometer. The reduction in pressure around the barometer leads it to expand. As the pump removes air from the jar, the mercury level rises.

29

The temperature at which water boils depends mainly on

A) Air Pressure B) Specific heat C) Density D) Relative humidity

Discuss

Answer & Solution

Answer: Option A

Solution:

The temperature at which water boils depends mainly on air pressure.

30

Air pressure is measured in which of the following units?

A) Steridian B) Kg/mts C) Newton D) Pascal

Discuss

Answer & Solution

Answer: Option D

Solution:

Air pressure is measured in Pascal.