Calculating acceleration due to gravity on a planet

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Homework Help Overview

The discussion revolves around calculating the acceleration due to gravity on a planet using data derived from a graph. The original poster provides initial conditions including velocities, time, and distance traveled by a ball, while also noting that air resistance is negligible.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to apply kinematic equations to find the acceleration due to gravity, expressing uncertainty about their calculations and the interpretation of the graph. Some participants question the accuracy of the data interpretation and the initial conditions provided.

Discussion Status

Participants are actively engaging with the original poster's method, with one suggesting that the approach seems correct based on the provided numbers. There is a recognition of a potential misunderstanding regarding the initial velocity and its implications for the calculations.

Contextual Notes

The original poster mentions a specific time value and the use of the Pythagorean theorem to determine vertical velocity, indicating that there may be constraints in the data or assumptions that need further exploration.

Bryon
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Homework Statement



The data is taken from a graph. The initial velocity is 31m/s. I found the horizontal velocity to be 21m/s. The time the ball travels is 5 seconds. The total distance the ball traveled is 105m. The ball lands at the same vertical level at which it starts. Air resistance can be neglected.


Homework Equations



Im pretty sure I have to use this equation, where t= 2.5.

v = v(initial) + at

I used the pythagoreum theorem to find the initial vertical velocity to be 22.8m/s. Then divided it by 2.5. What I came up with, -9.12, which is wrong.

I just can't find the acceleration due to gravity. It looks straight forward but I am missing a step. Any ideas?

Thanks!
 
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Your method appears to be correct and the answer follows from the numbers that you gave. If the answer is incorrect, then you need to make sure that you read the graph correctly. When you say "the initial velocity is 31 m/s", you mean the initial speed is 31 m/s, right?
 
Here is a link to the graph, which plots the velocity over time (sorry i didnt think to add it)

https://wug-s.physics.uiuc.edu/cgi/courses/shell/common/showme.pl?cc/DuPage/phys2111/fall/homework/Ch-03-04/golfball_plot/golfball_plot-1.jpg

Thanks for the help!
 
Last edited by a moderator:
Ahh, it was +9.12. However, I am not sure as to why it is positive.
 

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