i am unable to understand how (b) & (c) are correct & (d) incorrect.

Asked by araima2001 | 18th Mar, 2017, 08:19: PM

Expert Answer:

  • The effective weight, the difference between the weight of the sphere ( w = m x g = 1 x 10 = 10 N) and the upthrust (force opposite to the gravitational pull).
  • It should be assumed that the fluid is incompressible, that is, a flow in which the material density is constant within a fluid.
  • The upthrust in liquid = apparent loss of weight of the object, which is dependent on the density of the sphere. As the density is not given, it cannot be clearly concluded that this statement (B) is wrong.
  • Statement (C) that the direction of the external force must be horizontal is also an ambiguous statement as per the given conditions, therefore this statement as well cannot be termed incorrect.
  • Statement (D) is the only statement which can be clearly be termed as incorrect because, when the external force is suddenly removed, the acceleration of the body will not be purely equal to the acceleration of the flow of the liquid.
  • This acceleration of the sphere in the liquid will always be less than the acceleration of the flow of liquid due to the viscosity of the liquid and the inclined flow of the liquid with respect to the sphere.    

Answered by Abhijeet Mishra | 20th Mar, 2017, 06:30: PM

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