Fluid originally flows through a tube at a rate of 120 cm 3 /s. To illustrate th
ID: 778518 • Letter: F
Question
Fluid originally flows through a tube at a rate of 120 cm3/s. To illustrate the sensitivity of flow rate to various factors, calculate the new flow rate (in cm3/s) for the following changes with all other factors remaining the same as in the original conditions.
(a) Pressure difference increases by a factor of 1.40.
_________ cm3/s
(b) A new fluid with 3.00 times greater viscosity is substituted.
__________ cm3/s
(c) The tube is replaced by one having 4.00 times the length.
___________ cm3/s
(d) Another tube is used with a radius 0.100 times the original.
__________ cm3/s
(e) Yet another tube is substituted with a radius 0.100 times the original and half the length, and the pressure difference is increased by a factor of 1.50.
___________ cm3/s
Explanation / Answer
a) I hate wording like this.
If the pressure difference INCREASES by a factor of 1.40, then
new flow rate = 120cm³/s * (1 + 1.40) = 288 cm³/s
But they might have INTENDED us to answer
new flow rate = 120cm³/s * 1.40 = 168 cm³/s
(b) 120cm³/s / 3 = 40 cm³/s
(c) 120cm³/s / 3 = 40.0 cm³/s
(d) 120cm³/s * (0.1) = 0.012 cm³/s
(e) 120cm³/s * 2.5 * 1/½ * (0.1) = 0.06 cm³/s
with the same caveat as option (a).
so might have 120cm³/s * 1.5 * 1/½ * (0.1) = 0.036 cm³/s