Calculate time traveled from launch to land

  • Thread starter Thread starter ://Justice
  • Start date Start date
  • Tags Tags
    Launch Time
Click For Summary

Homework Help Overview

The discussion revolves around calculating the time of flight for a projectile launched at an angle, given its initial velocity and horizontal distance traveled. The problem involves kinematic equations and the decomposition of motion into horizontal and vertical components.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore different kinematic equations to relate distance, velocity, and time. There is confusion regarding the correct application of these equations, particularly in the context of projectile motion.

Discussion Status

Some participants have provided insights into the horizontal motion of the projectile, noting that there is no horizontal acceleration. Others have shared their attempts at solving the problem, leading to a realization of simpler approaches. There is an ongoing exploration of related questions regarding initial velocity and the effects of launch angle.

Contextual Notes

Participants are working under the constraints of homework guidelines, which may limit the information they can use or the methods they can apply. There is mention of empirical data that suggests a discrepancy in calculated time versus observed time, prompting further investigation into the assumptions made in the calculations.

://Justice
Messages
27
Reaction score
0

Homework Statement


So, this is pretty easy and simple, I am just missing something obvious here I am pretty sure. This stems from a question I asked earlier tonight.
Calculate the time it took from launch to land, given a velocity of 30.197m/s, and a distance traveled of 85m. (other irrelevant data: Object was initially launched at 33 degrees. Refer to https://www.physicsforums.com/showthread.php?p=2890328#post2890328 for more info)


Homework Equations


Perhaps, X=Xo+volt+.5at^2 ?


The Attempt at a Solution


So, I would use the formula X=Xo+volt+.5at^2, correct? But then, I get a bit confused...
-.5t^2=volt-X
divide by t
-.5t=Vo-X
t=-2(Vo-X)
but that is incorrect, I think... SO I dunno... Help, please... Thank you

Oh, wait... Am I maybe just way over-analyzing this? Would it be as simple as Distance/Velocity=Time? Therefore, V=30.197m/s , and D=85m, so 85/30.197=2.815s. But that seems a bit short. The empirical data is 4s (we must find the percent error), that is quite a large percent error...
 
Physics news on Phys.org
In the horizontal direction there is no acceleration.

s = vo*cos(theta)*t.
 
rl.bhat said:
In the horizontal direction there is no acceleration.

s = vo*cos(theta)*t.

Which is why I excluded 'a' when simplifying the equation, because a=0. Let me try that equation. Hmm... that seemed to yield a much more reasonable answer, 3.356s. That seems to be correct. Yeah, I get it now. It makes sense. Funny how things can just click and then you get it. Thank's for the help, I knew that it was really simple, I was just making it complicated.

Do you think you could help me really quickly with one more? Sorry.
Q: Find the initial velocity, when the object is shot at 70 degrees and took 6.5s to land. (hint: look at the y direction first this time)

Now, I know that there is the method of dividing it up into components of x and y, however I did not quite understand that. When calculating the initial velocity, given distance traveled and degree, I used Range = v02sin2θ/g which worked great (refer to https://www.physicsforums.com/showthread.php?p=2890328#post2890328 ), however, I don't know if that can apply to this too... Sorry, but physics is really confusing me at the minute
 
Q: Find the initial velocity, when the object is shot at 70 degrees and took 6.5s to land. (hint: look at the y direction first this time)

If it lands on the ground, vertical displacement y is zero. Vertical component of the velocity is vo*sinθ.
Use the equation
y = vo*sinθ* - 1/2*g*t^2

Substitute the values and find vo.
 

Similar threads

Replies
23
Views
2K
Replies
6
Views
3K
Replies
1
Views
2K
Replies
1
Views
1K
  • · Replies 15 ·
Replies
15
Views
10K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 5 ·
Replies
5
Views
1K