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: 478
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

Projectile Motion Problem Involving Initial Velocity and Gravity Only
    • Introductory Physics Homework Help
Replies
11
Views
145
Find the initial velocity ##U##
    • Introductory Physics Homework Help
Replies
3
Views
163
Projectile motion, initial height and range given, find initial velocity
    • Introductory Physics Homework Help
Replies
8
Views
576
Hitting a rocket with a projectile
    • Introductory Physics Homework Help
2
Replies
53
Views
3K
Is this projectile motion situation possible?
    • Introductory Physics Homework Help
Replies
6
Views
204
Circular motion to projectile motion
    • Introductory Physics Homework Help
Replies
18
Views
1K
Initial Position Discrepancy Involving Fluid Resistance
    • Introductory Physics Homework Help
Replies
5
Views
898
Projectile Motion: initial velocity problem
    • Introductory Physics Homework Help
Replies
1
Views
827
Find the initial velocity of a water rocket (mass changes)
    • Introductory Physics Homework Help
Replies
8
Views
2K
Find Projectile Flight Time Given Only Maximum Height
    • Introductory Physics Homework Help
Replies
4
Views
1K

Hot Threads

Recent Insights

Back
Top