Question

blood has travelled 20cm from a persons heart to their retinal artery .calculate the time taken for blood to flow from this persons heart to their retinal artery .show your working​

Answer 1

Answer:

Explanation

A

a

​

=8mm

2

           

              A

n

​

=4mm

2

         

             P

a

​

−P

n

​

=24 Pa

Let the speed of blood in artery and narrow part be  v

a

​

 and v

n

​

 respectively.

From continuity equation :     A

a

​

v

a

​

=A

n

​

v

n

​

∴   8v

a

​

=4v

n

​

       

⟹v

n

​

=2v

a

​

Using Bernoulli's equation :      

P

a

​

+ρgh

a

​

+

2

1

​

ρv

a

2

​

=  P

n

​

+ρgh

n

​

+

2

1

​

ρv

n

2

​

         

where h

n

​

=h

n

​

∴   P

a

​

−P

n

​

=

2

1

​

ρ(v

n

2

​

−v

a

2

​

)

∴  24=

2

1

​

×1.06×10

3

(4v

a

2

​

−v

a

2

​

)

           

⟹  v

a

​

=12.5×10

−2

  m/s