Tag: forces in fluids

Questions Related to forces in fluids

Complete the following sentence.

The stem of a hydrometer is made narrow because it _______its sensitivity.

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

  1. $increases$

  2. $decreases$

  3. $independent$

  4. $can't say$

Show answer
Correct Option: A
Explanation:

Hydrometer is an instrument used for determining the density of a liquid. It usually consists of a glass float with a long thin stem which is graduated. The glass float is a large hollow bulb which increases the buoyancy so that the hydrometer floats. The narrow stem increases the sensitivity of the hydrometer. The bottom of the hydrometer is made heavier by loading it with lead shots so that it floats vertically.

A hydrometer is used to measure , which of  the following quantity of a liquid ?

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

  1. Mass

  2. Volume

  3. Relative density

  4. Temperature

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Correct Option: C
Explanation:

A hydrometer is an instrument used to measure the relative density (or specific gravity) of liquids that is, the ratio of the density of the liquid to the density of water.

Which is the best instrument for testing the state of charge of car battery ?

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

  1. Voltmeter

  2. Ammeter

  3. Voltameter

  4. Hydrometer

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Correct Option: D
Explanation:

A hydrometer is used to test the state of charge of a battery cell. This is performed by measuring the density of the electrolyte, which is accomplished by measuring the specific gravity of the electrolyte. The greater the concentration of sulfuric acid, the more dense the electrolyte becomes.

The narrow stem in a hydrometer

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

  1. increases its sensitivity.

  2. increases upthrust on it

  3. raises its centre of gravity

  4. increases its size

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Correct Option: A
Explanation:

The narrow stem in a hydrometer increases its sensitivity.
The pressure increase with depth, so the lower part is made heavy to withstand high pressure.

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

Show answer
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

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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

Show answer
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.