Projectile Motion: Initial Velocity Derivation

In summary, the speaker is working on a school project involving water rockets and is struggling to produce an accurate mathematical model. They have compared their model's results to a water rocket simulator, but they are very different. They have also questioned the accuracy of their initial speed calculation and have requested a PDF version of their attached file. The speaker clarifies that their equation for determining range only applies to non-zero launch angles.
  • #1
PhysicsIBStudent
6
0
Hey guys, I am working on a school project and have fired some water rockets at different angles. I am now trying to compare theoretical results vs experimental results. But I am struggling to produce an accurate mathematical model.

I have attached my attempt to this post. It is quite long and possibly overly complex. I have not taken drag into account for this model.

I have compared the range results I got from my model to some from a water rocket simulator which was fed the same initial conditions but they are very different.

My question is whether my model is anywhere close to correct or where I went wrong. I used data from my water rocket to attempt to find the initial velocity of the rocket. I don't think my initial speed is correct tho.
 

Attachments

  • Initial velocity.pdf
    239.1 KB · Views: 477
Physics news on Phys.org
  • #2
Can you upload a PDF version of the file please? DOCX file format is not as secure as PDF format. Thanks.
 
  • #3
berkeman said:
Can you upload a PDF version of the file please? DOCX file format is not as secure as PDF format. Thanks.

Done. Please let me know if there are issues opening the pdf
 
  • #4
Equation (12) is suspicious. According to (12) what is the range when the projectile is launched horizontally (θ = 0)?
 
  • #5
Tom.G said:
Equation (12) is suspicious. According to (12) what is the range when the projectile is launched horizontally (θ = 0)?

Your right I forgot to mention this equation assumes you are launching from ground-level and the ground is flat. The formula only intends to work for non zero angles as launching at 0 degrees would result in a crash of some sort.
 

1. What is projectile motion?

Projectile motion is the motion of an object through the air or space under the force of gravity. It follows a curved path due to the constant downward acceleration of gravity.

2. How is initial velocity derived in projectile motion?

The initial velocity in projectile motion is derived using the equation v = u + at, where v is the final velocity, u is the initial velocity, a is the acceleration due to gravity, and t is the time. By rearranging this equation, we can solve for the initial velocity, u = v - at.

3. What is the formula for calculating the range of a projectile?

The formula for calculating the range of a projectile is R = (u^2 * sin(2θ)) / g, where R is the range, u is the initial velocity, θ is the angle of projection, and g is the acceleration due to gravity. This equation assumes that the initial height of the object is equal to the final height.

4. How does initial velocity affect the trajectory of a projectile?

The initial velocity has a direct impact on the trajectory of a projectile. A higher initial velocity will result in a longer range and a flatter trajectory, while a lower initial velocity will result in a shorter range and a steeper trajectory.

5. What are the other factors that can affect the trajectory of a projectile?

Aside from initial velocity, other factors that can affect the trajectory of a projectile include the angle of projection, air resistance, and the initial height of the object. These factors can alter the range and shape of the projectile's trajectory.

Similar threads

  • Introductory Physics Homework Help
Replies
3
Views
143
  • Introductory Physics Homework Help
Replies
8
Views
527
  • Introductory Physics Homework Help
2
Replies
53
Views
3K
  • Introductory Physics Homework Help
Replies
6
Views
181
  • Introductory Physics Homework Help
Replies
18
Views
1K
  • Introductory Physics Homework Help
Replies
5
Views
873
  • Introductory Physics Homework Help
Replies
1
Views
806
  • Introductory Physics Homework Help
Replies
8
Views
2K
  • Introductory Physics Homework Help
Replies
4
Views
1K
  • Introductory Physics Homework Help
Replies
5
Views
765
Back
Top