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WorksheetsConservation of Mass (Thermodynamics)
Total questions: 20
Worksheet time: 26mins
A dot over a symbol is indicating
time rate of change
phase change
spatial change
state change
In the formula of ṁ = AV/ν, what is ν?
density
specific weight
specific volume
enthalpy
(multiple answer) Specific volume is equal to
ρ1
volumemass
massvolume
volume1
If mass flow rate at inlet 1 and exit 3 are 20 kg/s and 30 kg/s, respectively, what is mass flow rate at inlet 2? Flow is steady
10 kg/s
50 kg/s
20 kg/s
30 kg/s
If the mass flow rate at inlet 1 is 15 kg/s, determine the mass flow rate at outlet 2. Assume the flow is steady.
10 kg/s
20 kg/s
15 kg/s
30 kg/s
Water is flowing from a pipe through inlet 1 at mass flow rate of 5 kg/s into a tank. Then, the water exit at mass flow rate of 3 kg/s through the pipe at the bottom-right of the tank. Take the red line as the control volume, is the water in the tank increases or decreases? What is the rate of change for the mass in the tank?
increases, 2 kg/s
decreases, 2 kg/s
increases, 8 kg/s
decreases, 8 kg/s
Volumetric flow rate only conserved when the flow is
steady
inviscid
incompressible
uniform
What is your matric number?
Choose all correct formula for mass flow rate
ρAV
νAV
ΔtΔm
νAV
Does the amount of mass entering a control volume have to be equal to the amount of mass leaving during an unsteady-flow?
Yes, mass in must equal mass out
No, it is not necessarily equal
Determine the mass flow rate of a given fluid whose density is 800 kg/m3, velocity and area of cross-section is 30 m/s and 20 cm2 respectively.
48 kg/s
4 800 kg/s
480 kg/s
480 000 kg/s
0.05 m3/kg of liquid flowing in a speed of 15 m/s and with an area of 12 m2. Calculate mass flow rate of liquid.
9 kg/s
3600 kg/s
9000 kg/s
3.6 kg/s
Water with density 1000 kg/m3 flows into a tank through a pipe with inside diameter 50 mm. The velocity of the fluid in the pipe is 2 m/s. The water flows out of the tank through a pipe with inside diameter 30 mm with a velocity of 2.5 m/s. How much is the change of the mass of water in the tank content after 20 minutes?
3591 kg
4591 kg
2591 kg
5591 kg
Mass flow rate can be determine by
(mass change) / (time taken)
volume change × area
volume × density
(velocity) / (cross sectional area)
Which is mass flow rate?
density × cross sectional area × velocity
cross sectional area × velocity
density × velocity
specific volume × area × velocity
Volume flow rate can be determined by
density × cross sectional area
specific volume × cross sectional area
(density change) / (time taken)
(volume change) / (time taken)
Which is volume flow rate?
density × cross sectional area × velocity
cross sectional area × velocity
density × velocity
specific volume × area × velocity
A garden hose attached with a nozzle is used to fill a 0.04 m3 bucket. If it takes 50 s to fill the bucket with water (density of 1000 kg/m3), determine the mass flow rates of water through the hose.
0.8 kg/s
8 kg/s
80 kg/s
0.008 kg/s
A garden hose attached with a nozzle is used to fill a 0.04 m3 bucket. If it takes 50 s to fill the bucket with water (density of 1000 kg/m3), determine the volume flow rates of water through the hose.
0.8 m3/s
8 m3/s
80 m3/s
0.0008 m3/s
Conservation of mass says that when the inflow mass flow rate is not balanced by the outflow mass flow rate, there will be a change of mass within the control volume (system).
True
False
