- #1
Calculating the Mass Flow Rate for Point C
AI Thread Summary
The mass flow rate at point C is calculated to be 2000 kg/s using the formula mass flow rate = ρ * dV/dt, with a velocity of 50 m/s and an area of 0.04 m². The discussion highlights that while the problem provides extra information, it is essential to discern what is necessary for solving the question. At point B, which has a wider pipe, the water must flow at a different speed to maintain the same mass flow rate as at point C. The participants agree that the extra details in the problem can sometimes be misleading, but arriving at the correct answer suggests clarity in understanding the concepts. Overall, the discussion emphasizes the importance of critical thinking in problem-solving.
- #2
Carid
- 277
- 1
Do you think these questions sometimes give you extra information in order for you to show that you know how to sort out the essential from the not useful?
At point B the pipe is wider than at C.
At B will the water be flowing faster, slower, or the same speed as a point C ?
Obviously the same amount of water must pass point B and point C.
So what can we say about the mass flow at B?
At point B the pipe is wider than at C.
At B will the water be flowing faster, slower, or the same speed as a point C ?
Obviously the same amount of water must pass point B and point C.
So what can we say about the mass flow at B?
- #3
stewartcs
Science Advisor
- 2,176
- 3
jimbo71 said:
Looks correct to me.
CS
- #4
Carid
- 277
- 1
Stewart,
Yes he's right, but the question gives a lot of unnecessary detail and I was trying to see if he was misled by it.
Yes he's right, but the question gives a lot of unnecessary detail and I was trying to see if he was misled by it.
- #5
jimbo71
- 80
- 0
I was a little mislead by the simplicity of the problem. Since the 6th grade, I've known some problems give more information than needed.
- #6
stewartcs
Science Advisor
- 2,176
- 3
Carid said:
Typically when students give the correct answer it implies that they were not mislead by it!
CS
Neglect gravity other than that of water; neglect friction.
F1=ρgsh=1000*10*1*(1+4)=50000 N;
F1=ρgsh=1000*10*0.1*4=4000 N;
F3=50000-4000=46000 N?
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook.
Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water.
I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system
$$M(t) = M_{C} + m(t)$$
$$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$
$$P_i = Mv + u \, dm$$
$$P_f = (M + dm)(v + dv)$$
$$\Delta P = M \, dv + (v - u) \, dm$$
$$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$
$$F = u \frac{dm}{dt} = \rho A u^2$$
from conservation of momentum , the cannon recoils with the same force which it applies.
$$\quad \frac{dm}{dt}...
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