AMU Engineering 2018 solved paper Solved Paper

If r be the radius of solid sphere having mass M and R be the radius of solid sphere having mass 8M
Mass of small solid sphere =

1

8

× Mass of large solid sphere

4

3

πr3ρ=

1

8

.

4

3

πR3ρ
r3=(

R

2

)3
r=

R

2

Terminal velocity of small solid sphere
v=

2

9

r2(ρ−σ)g

η

........(i)
Terminal velocity of large solid sphere
3nv=

2

9

R2(ρ−σ)g

η

...........(ii)
Dividing Eq. (i) by Eq. (ii), we get

v

nv

=

[ 2 9 r2(ρ−σ)g]∕η

[ 2 9 R2(ρ−σ)g]∕η

1

n

=

r2

R2

=

(R∕2)2

R2

=

1

4

n=4