Tag: physics

Questions Related to physics

Submarine's lactometers, hydrometers, etc. are designed according to __________.

  1. Archimedes principle

  2. Principles of hydrology

  3. Principles of fluid flow

  4. All of the above


Correct Option: A
Explanation:

Archimedes principle was an important work and has many application. It is used for designing submarines, ships etc. lactometer and hydrometer and also based on this principle and are used to check the purity of milk and density of liquids respectively.

Archimedes' principle states that the buoyant force applied to an object 

  1. is greater the weight of the fluid the object displaces

  2. is equal to the weight of the fluid the object displaces

  3. is less than the weight of the fluid the object displaces

  4. is zero


Correct Option: B
Explanation:

Archimedes' principle states that the buoyant force applied to an object is equal to the weight of the fluid the object displaces.

Archimedes principle works when the body is
  1. Partially immersed in a liquid

  2. Fully immersed in a liquid

  3. Both A and B

  4. This principle has nothing to do with the level of immersion of the body

Correct Option: C
Explanation:

Archimedes' Principle states that buoyant force acting on body upwards is equal in magnitude of the weight of liquid it displaces. Depending upon how much the body is immersed in liquid, and hence how much the weight of liquid is displaced, the buoyant force varies.

When an object is immersed in water, it displaces $20\,kg$ of water. How much is the buoyant force acting on the object in Newtons?
  1. $100$

  2. $200$

  3. $0$

  4. $400$


Correct Option: B
Explanation:

According to the Archimedes principle, the buoyant force acting on an object immersed in liquid is equal to the weight of liquid it displaces. Hence the buoyant force acting on the given object=$20kg\times 10m/s^2=200N$

Magnitude of buoyant force is given by 
  1. Newton's first law

  2. Archimedes principle
  3. Newton's second  law
  4. None of the above 


Correct Option: B
Explanation:

Archimedes principle, states that any body completely or partially submerged in a fluid (gas or liquid) at rest is acted upon by an upward, or buoyant force the magnitude of which is equal to the weight of the fluid displaced.

Archimedes principle is used for
  1. Determining the force applied on the object
  2. Determining the relative density of the object
  3. Determining the gravitational constant
  4. All the above


Correct Option: B
Explanation:
Hydrometer works on the Archimedes principle. The level at which it floats in liquid determines its relative density.
Quantitatively, $V _0dg=V _{immersed}\rho g$

$\implies $ relative density $\rho _r=\dfrac{d}{\rho}=\dfrac{V _{immersed}}{V _0}$
Fill in the blank.
It is the ______ which makes balloon to rise in air. 
  1. Upthrust

  2. Buoyant force

  3. Both A and B

  4. None


Correct Option: C
Explanation:

A balloon is filled with air at high pressure which leads to uprising of it because it experiences more buoyant force or we can say upthrust as they are same in this case.

Lactometers are based on
  1. Third law of motion

  2. Kepler's law

  3. Acceleration due to gravity

  4. Archimedes principle


Correct Option: D
Explanation:

Lactometer works on the Archimedes' Principle that a solid suspended in a fluid is buoyed by a force equal to the weight of the fluid displaced. If the milk sample is pure, then the lactometer floats on it and if it is adulterated or impure, then the lactometer sinks.

Fill in the blank. 

As per Archimedes principle the buoyant force on a submerged object is equal to_______ of liquid displaced by object. 

  1. Height

  2. Weight

  3. Nature

  4. Volume


Correct Option: B
Explanation:

According to the Archimedes principle, the buoyant force of a submerged object is equal to the weight of the liquid displaced.

$\therefore$ Buoyant force     $B = \rho gV$    where $\rho$ and $V$ is the density of liquid and volume of object respectively.

According to the law of floatation weight  of floating body is -

  1. Equal to the weight of liquid displaced

  2. Equal to the volume of liquid displaced

  3. Is greater than the weight of liquid displaced

  4. Is less than the weight of liquid displaced


Correct Option: A
Explanation:

According to Archimedes principle , weight of body in water or liquid is equal to the weight of the liquid displaced by it.