Tag: physics

Questions Related to physics

Give reasons as to why the lower end of a hydrometer is filled with mercury or lead.

physics forces in fluids hydrometer and lactometer comparing density - relative density principle of floatation and its applications

  1. to lower its CG point

  2. to increase the height of its CG point

  3. to rotate in water

  4. to jump in water

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Correct Option: A
Explanation:

The lower end of a hydrometer is filled with mercury or lead in order to make it heavy so that it remains upright 

A hydrometer is primarily used to measure ______ of a liquid.

physics forces in fluids hydrometer and lactometer comparing density - relative density principle of floatation and its applications

  1. density

  2. mass

  3. volume

  4. inertia

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Correct Option: A
Explanation:

Hydrometer is a device used to measure the specific gravity or density of a substance as an application of Archimedes principle.

Which of the following properties represent a hydrometer?
a. It helps to evaluate the relative density and purity of liquids.
b. The length of the hydrometer immersed in any liquid is directly proportional to the density of the liquid.
c. The relative density graduations on a hydrometer increase in the upward direction.
d. Water is regarded as a standard to find the relative density of any liquid using a hydrometer.

physics forces in fluids hydrometer and lactometer comparing density - relative density principle of floatation and its applications

  1. a, b and c

  2. a and d

  3. a, b and d

  4. b and d

Show answer
Correct Option: B
Explanation:

Hydrometer is a device used for directly measuring the relative density of a liquid with respect to water and hence helps to test the liquids purity. A hydrometer tube submerges less in a liquid of higher relative density and more in a liquid of lower relative density with regard to water. Thus the graduations on the hydrometer test tube show increase in relative density in the downward direction as it sinks less in a liquid of higher relative density.

Hydrometer is based on the principle of ___

physics forces in fluids hydrometer and lactometer comparing density - relative density principle of floatation and its applications

  1. Principle of buoyancy

  2. Principle of floatation

  3. Pascals law

  4. Charle's law

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Correct Option: B
Explanation:

Hydrometer is based on the principle of floatation i.e., the weight of the liquid object displaced by the immersed portion of the hydrometer is equal to the weight of the hydrometer. 

Match the following

1.Bulb filled with lead shots or mercury a. Increases sensitivity
2.The bulb helps the hydrometer to float b. Reduces center of gravity
3. Mercury c. Increases upthrust on the hydrometer
4. Narrow stem d. Gravity bulb
physics forces in fluids hydrometer and lactometer comparing density - relative density principle of floatation and its applications

  1. 1-b, 2-d, 3-c, 4-a

  2. 1-b, 2-c, 3-a, 4-d

  3. 1-a, 2-d, 3-b, 4-c

  4. 1-d, 2-c, 3-b, 4-a

Show answer
Correct Option: D
Explanation:

Common hydrometer consists of three main parts the stem, the large bulb (floating bulb) and the small bulb filled with mercury or lead shots (gravity bulb). The floating bulb increases the upthrust on the hydrometer because when it submerges in the water completely it increases the weight of the water displaced. The smaller bulb is filled with lead shots or mercury which helps in lowering the center of gravity which enables the hydrometer to float vertically in the liquid. Thus the smaller bulb is called the gravity bulb. The narrow stem helps the hydrometer to sink effectively when dropped in a liquid with higher or lower relative density thus increasing the sensitivity of the hydrometer.

Hydrometer is used to determine which of the following?

physics forces in fluids hydrometer and lactometer comparing density - relative density principle of floatation and its applications

  1. Specific gravity of liquids.

  2. Boiling point of water.

  3. Specific heat of a matter.

  4. Specific humidity

Show answer
Correct Option: A
Explanation:

Hydrometer is a devide used to determine the specific density of liquids.

A hydrometer is usually made of glass, and consists of a cylindrical stem and a bulb weighted with mercury to make it float upright. The liquid to test is poured into a tall container and the hydrometer is gently lowered into the liquid until it floats freely. The point at which the surface of the liquid touches the stem of the hydrometer correlates to specific gravity. Hydrometers usually contain a scale inside the stem, so that the person using it can read specific gravity. 

Hydrometers usually contain a scale inside the stem, so that the person using it can read specific gravity.Is the statement True or False

physics forces in fluids hydrometer and lactometer comparing density - relative density principle of floatation and its applications

  1. True

  2. False

Show answer
Correct Option: A
Explanation:
A hydrometer is usually made of glass, and consists of a cylindrical stem and a bulb weighted with mercury to make it float upright. The liquid to test is poured into a tall container and the hydrometer is gently lowered into the liquid until it floats freely. The point at which the surface of the liquid touches the stem of the hydrometer correlates to specific gravity. Hydrometers usually contain a scale inside the stem, so that the person using it can read specific gravity. 

The principle of working of hydrometer is based on Archimedes's principle 

physics forces in fluids hydrometer and lactometer comparing density - relative density principle of floatation and its applications

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

 archimedes principle states that weight lost by the body partially or fully immersed in a liquid is equal to the weight of the liquid displaced and hydrometer works on this principle.

so option (A) is correct

Hydrometer is used to measure 

physics forces in fluids hydrometer and lactometer comparing density - relative density principle of floatation and its applications

  1. Pressure

  2. Weight

  3. Density

  4. Mass

Show answer
Correct Option: C
Explanation:

Hydrometer is an instrument used for measuring the density of liquids.

A cube of ice has a iron piece frozen unside at.
The cube floats an a beakerfilled with water, when the ice melts then the level of water is beaker 

physics forces in fluids hydrometer and lactometer comparing density - relative density principle of floatation and its applications

  1. remains same

  2. level decreases

  3. level increases

  4. first increase ans decrese

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Correct Option: A