Velocity of .30 Cal Rifle After Firing a Bullet

In summary, in this scenario, a .30 caliber rifle with a mass of 6.4 kg fires a 33 gram bullet at 219 m/s in the positive direction. The rifle and the block of wood are mounted on separate carts atop a frictionless air track. The conservation of momentum principle can be applied to determine the velocity of the rifle after the bullet is fired, assuming the cart attached to the rifle is massless. Additionally, in the second part of the question, the velocity of the bullet and wood together can be solved for using the mass and velocity of the bullet and the total mass of the block and bullet.
  • #1
StotleD
21
0
Imagine I were to shoots a .30 caliber rifle at a 0.56 kg block of wood. The rifle and wood are mounted on separate carts that sit atop an air track (like a linear air hockey table--ie. frictionless). The 6.4 kg rifle fires a 33 gram bullet at 219 m/s in the positive direction. What would be the velocity of the rifle after the bullet is fired?
 
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  • #2
It seems like you need to apply conservation of momentum. In order to do that you would need to know the mass of the cart to which the rifle is attatched. Can it be assumed to be massless?
 
  • #3
Since the air track is frictionless, and every force has an equal and opposite force, the momentum of the rifle should equal the momentum of the bullet, yes?

PL
 
  • #4
But if the rifle is attached to the cart, much of the rifle's momentum will be transferred to it. They are being treated as one rigid body, I think.
 
  • #5
Yes, conservation of momentum would be the easiest, and from the information i think you would have to assume the cart is massless, otherwise the question is incomplete. Also the fact that it was shot at a block of wood seems irrelevant, unless there is a part B...
 
  • #6
The first part:
momentum before is equal to momentum after.
Mass of rifle x velocity of rifle = mass of bullet x velocity of bullet

I know the mass of the rifle and bullet and the velocity of the bullet,
so no I have to find the mass of the rifle.

The second part: (this is an inelastic collision-hit or 'stick collision'.)
Mass of bullet x velocity of bullet = total mass of block and bullet x
velocity of bullet and wood together.

I would have to solve for the velocity of the bullet and wood together.
 
  • #7
Okay, so do you understand how to do both parts now? You have all the information you need. Solve for the velocity of the rifle in the first one (as it seems the cart is massless), and solve for the velocity of the bullet and wood in the second one.
 
  • #8
Yes I got it. Thanks all!
 

What is the velocity of a .30 Cal rifle after firing a bullet?

The velocity of a .30 Cal rifle after firing a bullet can vary depending on several factors such as the type of bullet, the weight of the bullet, and the specific rifle being used. However, on average, the velocity of a .30 Cal rifle after firing a bullet can range from 2,700 feet per second (fps) to 3,100 fps.

What affects the velocity of a .30 Cal rifle after firing a bullet?

As mentioned before, the velocity of a .30 Cal rifle after firing a bullet can be influenced by several factors. The main factors that affect velocity include the type of bullet, weight of the bullet, barrel length, and powder charge. Generally, a heavier bullet will have a lower velocity compared to a lighter bullet, and a longer barrel will result in a higher velocity.

Can the velocity of a .30 Cal rifle after firing a bullet be measured?

Yes, the velocity of a .30 Cal rifle after firing a bullet can be measured using a chronograph. A chronograph is a device that measures the speed of an object by recording the time it takes for the object to pass between two sensors. By using a chronograph, the velocity of a .30 Cal rifle after firing a bullet can be accurately measured.

How does the velocity of a .30 Cal rifle after firing a bullet affect accuracy?

The velocity of a .30 Cal rifle after firing a bullet can greatly impact the accuracy of a shot. A higher velocity can result in a flatter trajectory and less bullet drop, making it easier to hit a target at longer distances. However, if the velocity is too high, it can cause the bullet to become unstable and decrease accuracy. It is important to find the optimal velocity for your specific rifle and ammunition for the best accuracy.

Is the velocity of a .30 Cal rifle after firing a bullet constant?

No, the velocity of a .30 Cal rifle after firing a bullet is not constant. As the bullet travels through the air, it will experience drag and lose velocity. The amount of velocity lost depends on the bullet's design, weight, and the distance it travels. For this reason, it is essential to consider the velocity at different distances when shooting with a .30 Cal rifle.

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