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Lesson 2 - Practice Problems

The liquid has a relative density of 0.80 and kinematic viscosity of 2.3 centistoke. Its unit weight is calculated as 7832.3 N/m3 and dynamic viscosity is calculated as 1.836 x10-3 Pa-s. A plate moving at 0.60 m/s requires a force of 2 N/m2, and the viscosity between the plates is calculated as 8.33x10-4 poise. Given a fuel consumption of 1kg/s and API gravity of 28, the minimum volume of the day tank is calculated as 97.41 m3/day.

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602 views4 pages

Lesson 2 - Practice Problems

The liquid has a relative density of 0.80 and kinematic viscosity of 2.3 centistoke. Its unit weight is calculated as 7832.3 N/m3 and dynamic viscosity is calculated as 1.836 x10-3 Pa-s. A plate moving at 0.60 m/s requires a force of 2 N/m2, and the viscosity between the plates is calculated as 8.33x10-4 poise. Given a fuel consumption of 1kg/s and API gravity of 28, the minimum volume of the day tank is calculated as 97.41 m3/day.

Uploaded by

adrian tan
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Sample Problem 1

A liquid at 20°C has a relative density of 0.80 and kinematic viscosity of 2.3 centistoke.
Determine its unit weight and dynamic viscosity.

Solution:
a. Unit weight = γ =ρg

Water at 20 °C has ρ = 998 kg/m3

γ =ρg = 998 kg/m3 x 0.80 x 9.81m/s2


γ = 7832.3 N/m3

b. Dynamic Viscosity = µd = µk ρ

µk = 2.3 centistoke = 2.3 x10-6 m2/s


µd = 2.3 x10-6 m2/s x 998 kg/m3 x 0.80

µd = 1.836 x10-3 Pa-s


Sample Problem 2

A plate 0.025mm distant from a fixed plate, moves at 60cm/s and requires a force of 2N per unit
area i.e., 2N/m2 to maintain this speed. Determine the fluid viscosity between the plates.
Solution:

dy = 0.025mm = 0.025x10-3 m

u = 60cm/s = 0.60 m/s


! = 2 N/m2
!"
!=µ
!#

!.#!$
(
2N/m2 = µ %
).)+,-.)&' $

Ns
µ = 8.33x10-5 x10 poise
$(

µ = 8.33x10-4 poise
Sample Problem 3

Calculate the minimum volume of day tank of 28°API having a fuel consumption of 1kg/s .
Given: 28°API , m = 1kg/s

Required: Volume V

Solution:
./..,
°API = - 131.5
0.1 @ .,.3°4

./..,
28°API = - 131.5
01

SG = 0.887
'
SG = , " = (SG)("H2O) = (0.887)(1000kg/m3)
'5+6

" = 887 kg/m3


" = 887 kg/m3

" = m/V
V = m/ " = 1kg/s / 887 kg/m3

V = 1/887 m3/s

m3 73))& 24 hr
V = 1/887 x ! "# x ! $%& = 97.41 m3 /day
&

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