# Solving Question: Speed of Ball with Rigid Cannon

• srhly
In summary, The cannonball will have a speed of 120 m/s after leaving the barrel, and if the cannon is mounted rigidly, the ball would travel even faster.
srhly
I had a two-part question but I've figured out the first part. A cannon with mass of 1960 kg fires a 24.5 kg ball horizontally. The cannonball has a speed of 120 m/s after it has left the barrel. For the first part I found that if the cannon was free to roll horizontally, its speed immediately after it was fired was 1.4907 m/s. The part I'm stuck on says imagine the same charge is used so total energy of cannon plus cannonball system is the same. Disregarding friction how much faster would the ball travel if the cannon were mounted rigidly and all other parameters remained the same? Answer in units of m/s.

What if you thought of momentum instead of energy? It is also conserved.

srhly said:
I had a two-part question but I've figured out the first part. A cannon with mass of 1960 kg fires a 24.5 kg ball horizontally. The cannonball has a speed of 120 m/s after it has left the barrel. For the first part I found that if the cannon was free to roll horizontally, its speed immediately after it was fired was 1.4907 m/s. The part I'm stuck on says imagine the same charge is used so total energy of cannon plus cannonball system is the same. Disregarding friction how much faster would the ball travel if the cannon were mounted rigidly and all other parameters remained the same? Answer in units of m/s.

It usually is adviceable to write down the exact question verbatim. Sometime, what you interpret as being asked is different than what it is actually asking. If I have understood your question here correctly, this is what it is asking for:

1. Since you already found the first part, you know the KE of the cannonball and the cannon separately.

2. If the cannon is fixed, then ALL the KE is now transferred to the cannonball. So the cannonball now will have the KE of what it had before PLUS the KE from the non-moving cannon. So this is its new KE for the cannonball. From here, find the new speed.

Zz.

srhly said:
I had a two-part question but I've figured out the first part. A cannon with mass of 1960 kg fires a 24.5 kg ball horizontally. The cannonball has a speed of 120 m/s after it has left the barrel. For the first part I found that if the cannon was free to roll horizontally, its speed immediately after it was fired was 1.4907 m/s. The part I'm stuck on says imagine the same charge is used so total energy of cannon plus cannonball system is the same. Disregarding friction how much faster would the ball travel if the cannon were mounted rigidly and all other parameters remained the same? Answer in units of m/s.
For item #1, did you calculate the cannon's recoil speed correctly?? The recoil speed should be (1.5 m/sec). Although the difference is small, it may indicate a problem somewhere. (Perhaps in copying the problem??) When using (1.5 m/sec) for item #1, the item #2 cannonball speed (with the cannon fixed) should be approx (120.75 m/sec).

~~

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## 1. What is the speed of the ball when it is fired from a rigid cannon?

The speed of the ball when it is fired from a rigid cannon depends on several factors such as the force applied, the mass of the ball, and the length of the cannon. It can be calculated using the equation v = √(2FL/m), where v is the speed, F is the force applied, L is the length of the cannon, and m is the mass of the ball.

## 2. How does the angle of the cannon affect the speed of the ball?

The angle of the cannon can affect the speed of the ball as it determines the direction of the force applied. The optimal angle for maximum speed would be 45 degrees, as it provides a balance between the vertical and horizontal components of the force.

## 3. Does the type of ball used affect the speed when fired from a rigid cannon?

Yes, the type of ball used can affect the speed when fired from a rigid cannon. A heavier ball would require more force to reach a certain speed, while a lighter ball would require less force. Additionally, the shape and aerodynamics of the ball can also impact its speed.

## 4. Can the speed of the ball be affected by external factors?

Yes, the speed of the ball can be affected by external factors such as air resistance, wind, and surface friction. These factors can either increase or decrease the speed of the ball, depending on their direction and magnitude.

## 5. How can the speed of the ball be measured accurately?

The speed of the ball can be measured accurately using various methods such as high-speed cameras, radar guns, and laser sensors. These devices can track the ball's movement and calculate its speed based on the time it takes to travel a certain distance.

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