Average speed of the gasoline as it leaves the nozzle?

[Punkyc7]

Homework Statement

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?

Homework Equations

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

The Attempt at a Solution

I don't really know were to start I have the volume of the tank as being .04m^3 I am not sure what to do next.

 

[superdave]

You want the flow rate equation.

Q=v*A

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

 

[Punkyc7]

Why is the flow rate in cm^3/s wouldn't it be squared because of area.
A would be = to 3.14159265*10^-4

 

[Punkyc7]

Also the books says the anwser is 1.1 meters a second i just don't know how it got to that

 

[rl.bhat]

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

 

[Punkyc7]

is that calculus because I haven't been taught how to use or apply it to these types of problems.

 

[rl.bhat]

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.

 

[Punkyc7]

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

 

[rl.bhat]

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

 

[Punkyc7]

Thanks i got it for some reason i couldn't get to that equation before but now i get it sorry for taking up your time.

 

[rl.bhat]

It is OK.