How to Calculate the Speed of a Spud Gun Bullet?

[Mirzet99]

Homework Statement

I have to calculate the speed with which a spud gun fires a bullet. The length of barrel is 1 meter.

Homework Equations

v=s/t , where v=velocity; s=distance; t=time

The Attempt at a Solution

NOTE: I will easily calculate distance. I have spud gun but I don't know the way how to calculate that speed which is not average speed of bullet.[/B]

 

[haruspex]

Homework Statement

I have to calculate the speed with which a spud gun fires a bullet. The length of barrel is 1 meter.

Homework Equations

v=s/t , where v=velocity; s=distance; t=time

The Attempt at a Solution

NOTE: I will easily calculate distance. I have spud gun but I don't know the way how to calculate that speed which is not average speed of bullet.[/B]

You cannot calculate anything without some data. The length of the barrel is clearly not enough. What else do you know or can know?

 

[Mirzet99]

You cannot calculate anything without some data. The length of the barrel is clearly not enough. What else do you know or can know?

I don't know anything else. My profesore wants me to do that but he doesn't want to tell me how. I think he doesn't know also..

 

[Chestermiller]

Please describe how a spud gun works. (I know how a spud gun works. I'm just asking you to describe it in words). I'm sure that will give you some ideas on what you need to do to answer this question.

Chet

 

[Mirzet99]

Please describe how a spud gun works. (I know how a spud gun works. I'm just asking you to describe it in words). I'm sure that will give you some ideas on what you need to do to answer this question.

Chet

Please describe how a spud gun works. (I know how a spud gun works. I'm just asking you to describe it in words). I'm sure that will give you some ideas on what you need to do to answer this question.

Chet

In barrel, I put potato. In this lower,biggest part,I put gasoline and with igniter, I burn it. Explosion happens and that gas wants to spread. But it is closed from all sides,expect this one where is potato. That's the way how it works.

 

[Chestermiller]

If I remember correctly, the spud is situated near the forward end of the barrel, correct? How far back is typical?

You need to know the volume of the chamber behind the spud. Approximately what volume is that (of air to start with). You also need to know approximately how much gasoline is injected into the chamber. So, how much??

What is the balanced equation for the reaction of air and gasoline? What is the heat of reaction of gasoline and oxygen? Based on the stoichiometry of the reaction, how many moles of gas will be in the chamber after all the gasoline has burned?

This should get you started.

Chet