A spherical ball is dropped in a long column of viscous liquid. Which of the following 
graphs represent the variation of 
(i) gravitational force with time 
(ii) viscous force with time 
(iii) net force acting on the ball with time? 
 
1.  Q, R, P

 


A sphere of solid material of relative density 9 has a concentric spherical cavity and just sinks in water. If the radius of sphere be R, then the radius of cavity (r) will be related to R as
1.  r3 = \({{8}\over{9}}\)R3
2.  r3 = \({{2}\over{3}}\)R3
3.  r3 = \({{\sqrt{8}}\over{3}}\)R3
4.  r3 = \({{\sqrt{2}}\over{3}}\)R3

 

Subtopic:  Archimedes' Principle |
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A uniform magnetic field parallel to the plane of paper, exsisted in space initially directed from left to right. When a bar of soft iron is placed in the field parallel to it, the lines of force passing through it will be represented by figure.
 
1.