Solving Work Done by Gas on a Bullet in a Rifle Barrel

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In summary, the problem involves a 103 g bullet fired from a rifle with a barrel .796 m long. The force exerted on the bullet by the expanding gas is variable and can be represented by the equation F = a + bx - cx^2. To determine the work done by the gas on the bullet, we can use the formula W_F = \int _{x_1}^{x_2}Fdxya, where x represents the displacement of the bullet within the barrel. If the barrel is 1.136 m long, the work done can also be calculated using this formula."
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JamesL
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Heres the problem:

A 103 g bullet is fired from a rifle having a barrel .796 m long. Assuming the origin is placed where the bullet begins to move, the force exerted on the bullet by the expanding gas is F = a + bx - cx^2, where a = 10600 N, b = 5000 N/m, c = 39400 N/m^2, with x in meters.

Determine the work done by the gas on the bullet as the bullet travels the length of the barrel.

Also, if the barrel is 1.136 m long, how much work is done?

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I wasnt sure whether or not to treat this problem as a variable force one... the only way i really know how to do that is by using a "spring-like" constant, but I am not sure if that is really applicable in this problem.

Could anyone point me in the right direction?
 
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  • #2
Yes, the force is not constant in this problem so you have to treat it as a variable force problem. If you draw a graph of F as a function of X, what would it look like? What would the area below the graph represent? How can you find that area? Hint:
[tex]W_F = \int _{x_1}^{x_2}Fdx[/tex]
 
  • #3
ya...u can think of it this way...the force of the expanding gas on the bullet changes because it depends on the displacement x and the x iz changing...x changes frm what to what? 0 to .796...[so the integral can be interpreted az the force [F] changing with respect to x [dx] from x1 to x2]

- Mr. Kamadolli
 

FAQ: Solving Work Done by Gas on a Bullet in a Rifle Barrel

What is "Work Done by Gas on a Bullet in a Rifle Barrel"?

"Work Done by Gas on a Bullet in a Rifle Barrel" refers to the energy transferred from expanding gases to a bullet when it is fired from a rifle. This energy is responsible for propelling the bullet out of the barrel and towards its target.

How is work done by gas on a bullet calculated?

The work done by gas on a bullet can be calculated using the equation W = F x d, where W is work, F is the force exerted by the expanding gases, and d is the distance the bullet travels in the barrel. This calculation takes into account the pressure of the gas and the cross-sectional area of the barrel.

What factors affect the work done by gas on a bullet?

The work done by gas on a bullet is affected by several factors, including the pressure and temperature of the gas, the length and diameter of the barrel, and the weight and velocity of the bullet. Additionally, the type and amount of gunpowder used can also impact the work done by gas on a bullet.

Why is understanding work done by gas on a bullet important?

Understanding the work done by gas on a bullet is important for several reasons. First, it allows us to accurately predict the trajectory and velocity of a bullet, which is crucial for marksmanship and ballistics. Additionally, it helps us design more efficient and effective firearms and ammunition.

How does the work done by gas on a bullet affect recoil?

The work done by gas on a bullet is directly related to the recoil of a firearm. The more work done by the expanding gases, the greater the recoil force and the stronger the kickback felt by the shooter. This is why firearms with more powerful ammunition tend to have stronger recoil.

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