Calculate acceleration due to gravity

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Homework Help Overview

The discussion revolves around calculating the acceleration due to gravity on a different planet, based on a scenario where a stone is thrown horizontally from a height of 200m and takes 4 seconds to reach the ground. The problem involves understanding the motion of the stone under the influence of gravity, with the initial vertical velocity being zero.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the application of the kinematic equation Δy = v0t + 1/2 at², questioning the initial vertical velocity and the resulting calculations for gravity. There is confusion regarding the correct interpretation of the time and height values leading to differing conclusions about the acceleration due to gravity.

Discussion Status

The discussion is ongoing, with participants expressing differing views on the calculations. Some participants have suggested that the original poster's reasoning appears sound, while others have pointed out potential issues with the problem setup or answer keys. There is no explicit consensus on the correct value for acceleration due to gravity.

Contextual Notes

There is mention of potential errors in answer keys and the possibility of misinterpretation of the problem statement, which may affect the calculations. The original poster's approach and the responses indicate a need for clarification on the assumptions made in the problem.

rasen58
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Homework Statement


A stone is thrown horizontally from a cliff on a different planet with a speed of 10 m/s. The cliff has height 200m, and takes 4 s to hit the ground. Assume no air friction. What is the acceleration due to gravity on this planet.

Homework Equations


Δy = v0t + 1/2 at2

The Attempt at a Solution


I thought the initial vertical velocity would be 0 since it's thrown horizontally, so the first term of the equation disappears. And they give you t = 4, so I did 200*2/16 = 25 m/s^2.
But apparently the answer is 5 m/s^2.
Why?
 
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rasen58 said:
Why?
rasen58 said:
1/2 at2
One half "a" times "t" squared.
 
rasen58 said:

Homework Statement


A stone is thrown horizontally from a cliff on a different planet with a speed of 10 m/s. The cliff has height 200m, and takes 4 s to hit the ground. Assume no air friction. What is the acceleration due to gravity on this planet.

Homework Equations


Δy = v0t + 1/2 at2

The Attempt at a Solution


I thought the initial vertical velocity would be 0 since it's thrown horizontally, so the first term of the equation disappears. And they give you t = 4, so I did 200*2/16 = 25 m/s^2.
But apparently the answer is 5 m/s^2.
Why?
Your answer (as well as your analysis) looks good to me !

I agree it's 25 m/s2 .
 
Get used to facing problems/exercises in which people have swapped quantities/values to be found from the problem statement for other "given" values, and failed to correct answer keys.
 
Okay, so I'm right. Thank you.
 

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