 ### 5 Examples of Fluid Mechanics Practice Questions and Answers

Examples of Fluid Mechanics Problems and Discussion – Fluid mechanics (Fluid mechanics) are the branch of physics that studies fluids (liquids, gases and plasmas) and the forces acting on them. Fluid mechanics can be divided into:

• Fluid statics, the study of the state of fluids at rest;
• Fluid kinematics, the study of fluids in motion; and
• Fluid dynamics, the study of the effects of forces on fluids in motion.

Fluid mechanics can be very complicated mathematically, and it is very appropriate to be solved by numerical methods, usually by means of computer calculations.

Computational Fluid Dynamics, is one of the disciplines devoted to solving fluid mechanics problems with a numerical approach.

## 1 – 5 Fluid Mechanics Problems and Discussion

1. Ahmad fills a bucket that has a capacity of 20 liters with water from a faucet like the following picture!

If the cross-sectional area of ​​a faucet with a diameter of D2 is 2 cm² and the water flow velocity is

at the faucet is 10 m/s determine:

a) Water discharge

b) Time required to fill the bucket 2. The underground water pipe has a shape like the following picture!

If the cross-sectional area of ​​the large pipe is 5 m2, the cross-sectional area of ​​the small pipe is 2 m2 and the velocity of the water flow in the large pipe is 15 m/s, determine the velocity of the water as it flows in the small pipe!

Discussion Continuity equation

A1v1 = A2v2

(5)(15) = (2)v2

v2 = 37.5 m/s

3. A horizontal pipe, flowing water from end A to end B. Cross section A = 20 cm² and cross section B = 10 cm². If the water discharge is 10-³ m³/s, what are the velocities at A and at B? 4. A 150 mm pipe carries 0.08 m3/s, it branches into two pipes one diameter is 50 mm and the other is 100 mm in diameter. If the velocity in the 50 mm pipe is 12 m/s, what is the velocity in the 100 mm pipe?

Discussion :

Dick :

dB : 50 mm = 0.05 m

dC : 100 mm = 0.1 m

B : 12 m/s

QA : 0.08 m3/s

Dit : C… ? 5. The pipe for distributing water is attached to a house wall as shown in the following picture! The ratio of the cross-sectional area of ​​a large pipe and a small pipe is 4: 1.

The position of the large pipe is 5 m above the ground and the small pipe is 1 m above the ground. The velocity of water flow in a large pipe is 36 km/hour with a pressure of 9.1 x 10^5 Pa. Define:

a) Velocity of water in small pipe

Discussion Data :

h1 = 5 m

h2 = 1 m

v1 = 36 km/h = 10 m/s

P1 = 9.1 x 105 Pa

A1 : A2 = 4 : 1

a) Velocity of water in small pipe

Continuity Equation:

A1v1 = A2v2

(4)(10) = (1)(v2)

v2 = 40 m/s