Need help with projectile motion problem

In summary, the conversation discusses a record-setting pumpkin launch at a competition and the optimal angle for maximum range. It also mentions a book on ballistics and the use of numerical methods for low ballistic coefficient objects. The conversation ends with a humorous anecdote about a shotgun test that was cut short.
  • #1
kwaber1
1
0
I found this interesting problem on the internet, but I think there is not enough infromation to solve.
"At the 1998 Punkin Chunkin World Championship, a pneumatically-driven device called the "Aludium Q36 Pumpkin Modulator" was able to project a 3.6-4.5 kg (8-10 pound) pumpkin intact for a total distance of 1227.23 m (4026.32 feet, how many feet are in a mile?). What was the muzzle velocity (magnitude and direction) of the record-setting pumpkin?"

Most range formula problems give you 2 of the 3 variables to solve for the third R, vo or Θ
Any help would be appreciated.
 
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  • #2
Neglecting the effects of friction (a necessary but absurd assumption) there is a value of ##\theta## that gives you the maximum range. I think it's understood that the pumpkin was chucked at this angle.
 
  • #3
The optimal angle for maximum range in a vacuum is 45 degrees. When the effect of air resistance is included, it's between 30 and 45 degrees.

The definitive book on the subject is Modern Practical Ballistics, by Arthur J. Pejsa. The equations in that book may not cover objects with the (low) ballistic coefficient of pumpkins. If so, numerical methods are needed.

For a shotgun with birdshot fired at (very roughly) 30 degree elevation, the pellets come almost straight down at maximum range. This from a test where my dad had my mother shoot at him. Unfortunately, she had no experience with a double barrel shotgun with double triggers, so she fired both barrels at the same time and got knocked down from the recoil. That ended further testing.
 
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Likes btlang
  • #4
JRMichler said:
For a shotgun with birdshot fired at (very roughly) 30 degree elevation, the pellets come almost straight down at maximum range. This from a test where my dad had my mother shoot at him. Unfortunately, she had no experience with a double barrel shotgun with double triggers, so she fired both barrels at the same time and got knocked down from the recoil. That ended further testing.

This is a fascinating report. One could speculate all day about your parents relationship (lol!). Considering the legal/moral/ethical aspects of this situation, it is probably best that testing ended at that point.
 

Related to Need help with projectile motion problem

1. What is projectile motion?

Projectile motion is the motion of an object through the air, under the influence of gravity, after it has been thrown or launched.

2. How do you solve a projectile motion problem?

To solve a projectile motion problem, you need to break it down into two components: the horizontal and vertical motion. You can then use equations of motion and the constant acceleration due to gravity to solve for the final position, velocity, and time.

3. What are the key factors that affect projectile motion?

The key factors that affect projectile motion are the initial velocity, the angle of launch, air resistance, and the gravitational pull of the Earth.

4. How does the angle of launch affect projectile motion?

The angle of launch affects projectile motion by determining the trajectory of the object. A smaller angle will result in a shorter and lower trajectory, while a larger angle will result in a longer and higher trajectory.

5. What are some real-life applications of projectile motion?

Projectile motion has many real-life applications, such as in sports like basketball, soccer, and golf. It is also used in engineering to design and test projectiles, and in military applications like missile launches.

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