6. The discharge in m³ / s for laminar flow through a pipe of diameter 0.04 m having a centre line velocity of 1.5 m/s is
   

1. 1. 	3π
      	50

      
      

   
   
   

   2. 	3π
      	2500

      
      

   
   
   

   3. 	3π
      	5000

      
      

   
   
   

   4. 	3π
      	10000

   
   
   

---

1. View Hint View Answer Discuss in Forum

   u_max = 2 u_avg
   u_max = 2 u_avg
   1.5 = 2u_avg
   

   uavg =	1.5	m /s
   	2

   
   Q = A × V = A × u_avg
   

   Q =	π	d2 × uavg
   	4

   
   

   =	π	× (0.04)2 ×	1.5	=	3π	m3 /s
   	4		2		10000

   
   

   Correct Option: D

   u_max = 2 u_avg
   u_max = 2 u_avg
   1.5 = 2u_avg
   

   uavg =	1.5	m /s
   	2

   
   Q = A × V = A × u_avg
   

   Q =	π	d2 × uavg
   	4

   
   

   =	π	× (0.04)2 ×	1.5	=	3π	m3 /s
   	4		2		10000

   
   

---

7. Shown below are three tanks, tank 1 without an orifice tube and tanks 2 and 3 with orifice tubes as shown. Neglecting losses and assuming the diameter of orifice to be much less than that of the tank, write expressions for the exit velocity in each of the three tanks.
   
   

1. 1. V₁ = √2gH
      

   
   
   

   2. V₂ = √2g(H + L)
      

   
   
   

   3. V₃ = √2g(H + L)

   
   
   

   4. All of these

   
   
   

---

1. View Hint View Answer Discuss in Forum

   V₁ = √2gH
   V₂ = √2g(H + L)
   V₃ = √2g(H + L)

   Correct Option: D

   V₁ = √2gH
   V₂ = √2g(H + L)
   V₃ = √2g(H + L)

---

---

8. For a fully developed flow through a pipe, the ratio of the maximum velocity to the average velocity is _________(fill in the blanks)
   

1. 1. Two

   
   
   

   2. Three

   
   
   

   3. Zero

   
   
   

   4. None of these

   
   
   

---

1. View Hint View Answer Discuss in Forum

   Two

   Correct Option: A

   Two

---

9. As the transition from laminar to turbulent flow is induced in a cross flow past a circular cylinder the value of the drag coefficient drops.

1. 1. False

   
   
   

   2. True

   
   
   

   3. Neither True nor False

   
   
   

   4. None of these

   
   
   

---

1. View Hint View Answer Discuss in Forum

   True

   Correct Option: B

   True

---

---

10. A cubic block of side L and mass M is dragged over an oil film across table by a string connects to a hanging block of mass m as shown in figure. The Newtonian oil film of thickness h has dynamic viscosity μ and the flow condition is laminar. The acceleration due to gravity is g. The steady state velocity V of block is
    
    

1. 1. 	Mgh
      	μL²

      
      

   
   
   

   2. 	Mgh
      	μ

      
      

   
   
   

   3. 	mgh
      	μL²

      
      

   
   
   

   4. 	mgh
      	μ

   
   
   

---

1. View Hint View Answer Discuss in Forum

   τ = μ		du
   		dy

   
   du = V – O – V
   dy = h
   

   τ = u	V	...(1)
   	h

   
   

   Also , τ =	F
   	A

   
   where F = mg , A = L²
   

   ∴ τ =	mg	......(2)
   	L2

   
   By (1) (2), we get
   

   V =	mgh
   	uL2

   
   

   Correct Option: C

   τ = μ		du
   		dy

   
   du = V – O – V
   dy = h
   

   τ = u	V	...(1)
   	h

   
   

   Also , τ =	F
   	A

   
   where F = mg , A = L²
   

   ∴ τ =	mg	......(2)
   	L2

   
   By (1) (2), we get
   

   V =	mgh
   	uL2

   
   

---