Finding Acceleration Due To Gravity

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Homework Help Overview

The problem involves determining the acceleration due to gravity on a fictional planet inhabited by an alien species called Gaks. The scenario describes a Gak dropping a ball from rest and measuring the time it takes to fall a specific distance.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the original poster's method for calculating velocity and question its validity, noting that it only provides average speed rather than instantaneous speed. There is a suggestion to find a formula that relates distance and time without needing the radius of the planet.

Discussion Status

The discussion is ongoing, with participants exploring different formulas and questioning the assumptions made about the problem. Some guidance has been offered regarding the use of kinematic equations, but no consensus has been reached on how to proceed without additional information.

Contextual Notes

Participants note the lack of data regarding the radius and mass of the planet, which complicates the use of certain gravitational formulas. This missing information is acknowledged as a significant constraint in solving the problem.

Dave Johnson
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Homework Statement


A Gak it a type of alien that lives on a planet in another galaxy. One day a Gak decides to find out a little more about his planet. He drops a ball (it starts at rest) with a mass of 4.88 kg and notes that it takes 0.712 s to fall a distance of 4.04 m.

What is the acceleration due to gravity on the Gak’s planet?

Homework Equations


mgh = 0.5mv^2

The Attempt at a Solution


V = 4.04/0.712 = 5.67m/s
g = (0.5V^2)/h = [0.5(5.67)^2]/4.04 = 3.98ms^-2

However, answer is incorrect. Can someone kindly help me please?
 
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Your method of getting v is wrong. It only gives you the average speed. The instantaneous speed of the ball is changing all the time, as it falls. You should be able to use a formula which does not involve the speed, but involves only the quantities for which the data is given.
 
I see... But i can't seem to find any formula without any given radius.
 
Sorry. What is the radius we are talking about here?
 
the formula for acceleration due to gravity is g = G*M/R^2. R is the radius
 
But the data for the radius and mass are not given. So how do you use that?
 
Yap that why i said its hard to solve this question without radius.
 
Can you think of a formula that connects the distance the ball drops to time?
 
d = vt + (1/2)at2?
 
  • #10
What is v in your formula?
 
  • #11
0
 
  • #12
So now you can find g, right?
 
  • #13
yap cheers
 

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