Question

the parallactic angle subtended by a distance star is 0.76 on the earth's orbital diameter (1.5*1011m). calculate the distance of the star from the earth..

Answer 1

distance of star from earth = D
parallax angle= 0.76 rad
distance between two observation points = d= 1.5 x 10¹¹m

so, as
D = d/ Ф
D= 1.5 x 10¹¹/ 0.76
 = 1.97 x 10¹¹m

Answer 2

Explanation:

In the first tube

 Rate of flow = Q

Radius = a

Pressure difference = P

length of the tube = l

coefficient of viscosity = л

From Poiseuille’s equation;

Q= λpa²/ 8лl

Now, let the new rate of flow be Q1, 

 radius = a/2 

pressure difference = 2p 

New Poiseulle’s equation;

Q1= λ 2p (a/2)²/8лl

dividing both eq we get

Q1/ Q= 1/8

Q1= Q/8