Comparing two methods of finding muzzle velocity?

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In summary, in this lab we used a ballistic pendulum to find velocity. The equation provided was v= M/m * radical(2gRcm(1-cosθ)). However, there was a question about finding muzzle velocity using the conservation of momentum/energy formula which did not give similar results. It was later realized that this discrepancy was due to not accounting for nonconservative forces, specifically air resistance and friction. Once these were taken into consideration, the same answer was obtained.
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Homework Statement


In this lab we used a ballistic pendulum to find velocity.

They gave us the equation (below) to find the velocity of the ball that we shot and want to know if there's another way of finding muzzle velocity. I thought of using the Conservation of Momentum/Energy formula but I'm not getting similar results.

θ=25
M=4.5kg
m=.7kg
Rcm=.3m

Homework Equations



v= M/m * radical(2gRcm(1-cosθ))

The Attempt at a Solution


I'm getting something like 2.5 or so while the conservation equations lead to a decimal.
I figured it out. I didn't take into account the nonconservative forces.
 
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I was using the conservation of momentum and energy equations as if no nonconservative forces were acting on the system. However, there is air resistance and friction in this case. Once I accounted for that, I got the same answer.
 

Related to Comparing two methods of finding muzzle velocity?

1. What is muzzle velocity and why is it important in comparing methods?

Muzzle velocity is the speed at which a projectile leaves the barrel of a firearm. It is an important factor in determining the effectiveness and accuracy of a weapon, as well as its range and potential for causing damage.

2. What are the two methods commonly used to find muzzle velocity?

The two methods are chronographs and ballistic pendulums. Chronographs use sensors to measure the time it takes for a projectile to pass through two points, while ballistic pendulums use the swing of a pendulum to determine the energy of a projectile and then calculate its velocity.

3. What are the pros and cons of using a chronograph vs a ballistic pendulum?

Chronographs offer more precise measurements and are easier to use, but they can be affected by weather conditions and require frequent calibration. Ballistic pendulums are less precise and more difficult to set up, but they are not affected by weather and do not require calibration.

4. How do these methods compare in terms of accuracy?

Both methods can provide accurate measurements, but chronographs tend to be more precise due to their ability to measure the time it takes for a projectile to pass through two points. However, the accuracy of both methods can be affected by factors such as user error, weather conditions, and the quality of equipment.

5. Which method is more commonly used in scientific research and why?

Chronographs are more commonly used in scientific research due to their precision and ease of use. They also allow for multiple measurements to be taken quickly, making them more efficient for larger studies. However, ballistic pendulums are still used in some research studies, particularly for measuring the velocity of larger projectiles or those with irregular shapes.

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