Please solve q 206?

enter image source here

2 Answers

D. 2/3pir^4rhog23πr4ρg

Explanation:

on applying conservation of energy,
KE_i.+PE_i=KE_f+PE_fKEi.+PEi=KEf+PEf
=0+"mg"_i-"buoyant force"_i=0+"mg"_f-"buoyant force"_f+WD0+mgibuoyant forcei=0+mgfbuoyant forcef+WD
= [0.5 * 4/3 * 3.14 * r3 * g].r – [d * 2/3 * 3.14 * r3 * g].r+W.D.
=[d * 4/3 * 3.14 * r3 * g].r -[d * 2/3 * 3.14 * r3 * g].r = W.D
=W.D = 2/3(3.14*r^4rhog)= 2/3pir^4rhog

Apr 8, 2018

The answer is "option (4)"

Explanation:

The force (to overcome the buoyancy) necessary to push down the sphere is

F=2/3xxpixxr^3xxg

The distance is d=r

The work done is

W=Fxxd=2/3pir^3rhogxxr=2/3pir^4rhog

The answer is "option (4)"