# Average speed of the gasoline as it leaves the nozzle?

1. Oct 21, 2009

### Punkyc7

1. The problem statement, all variables and given/known data
It takes 2 minutes to fill a gas tank with 40 liters of gasoline. If the nozzle is 1cm in radius, what is the average speed of the gasoline as it leaves the nozzle?

2. Relevant equations
A1V1=A2v2 or 1/2pv^2 + pgh+p=constant

3. The attempt at a solution
I dont really know were to start I have the volume of the tank as being .04m^3 Im not sure what to do next.

Last edited: Oct 21, 2009
2. Oct 21, 2009

### superdave

Re: Fluids

You want the flow rate equation.

Q=v*A

Where Q = flowrate in cm^3/s and A is the cross-sectional area.

3. Oct 21, 2009

### Punkyc7

Re: Fluids

Why is the flow rate in cm^3/s wouldnt it be squared because of area.
A would be = to 3.14159265*10^-4

4. Oct 21, 2009

### Punkyc7

Re: Fluids

Also the books says the anwser is 1.1 meters a second i just dont know how it got to that

5. Oct 21, 2009

### rl.bhat

Re: Fluids

Volume V = X *A
V/t = X/t*A = v*A, where v is the velocity of the liquid flow through the nozzle.

6. Oct 21, 2009

### Punkyc7

Re: Fluids

is that calculus because I havent been taught how to use or apply it to these types of problems.

7. Oct 21, 2009

### rl.bhat

Re: Fluids

NO. Not at all.
In the problem what is flow rate V/t?
If you freeze the outflow of one second, whose length is L and area of cross section is A, what is the volume of the liquid?
(L/one second) is the average velocity of out flow.

8. Oct 21, 2009

### Punkyc7

Re: Fluids

the volume is .04m^3, cross sectional area is .01^2*pi

9. Oct 21, 2009

### rl.bhat

Re: Fluids

dQ/dt = Volume/time. What is the time taken to fill the tank?
Velocity = (dQ/dt)/Area.

10. Oct 21, 2009

### Punkyc7

Re: Fluids

Thanks i got it for some reason i couldnt get to that equation before but now i get it sorry for taking up your time.

11. Oct 21, 2009

Re: Fluids

It is OK.