How Does a Grapefruit Affect Spring Compression?

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Homework Help Overview

The discussion revolves around a physics problem involving a grapefruit attached to a vertical spring. The problem requires determining the net force and acceleration of the grapefruit when it is displaced below the spring's unstretched position, as well as the equilibrium position considering air resistance.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the calculation of net force using the gravitational force and spring force. There is an attempt to clarify the units and values used in the calculations, particularly the mass of the grapefruit.

Discussion Status

Some participants are questioning the calculations presented, specifically the mass conversion and the resulting net force value. There is an ongoing exploration of the correct approach to the problem, but no consensus has been reached yet.

Contextual Notes

Participants are addressing potential errors in the mass conversion from grams to kilograms and discussing the implications for the calculations. The problem also involves assumptions about air resistance and its effect on the spring's equilibrium position.

physicsdb
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question: a grapefruit of mass 289g is attached to an unstretched vertical spring of force constant 18.7 N/m, and is allowed to fall.

a) determine the net force and the acceleration on the grapefruit when it is 10.0 cm below the unstretched position and moving downward.

b)air resistance will cause the grapefruit to come to rest at some equilibrium position. How far will the spring be stretched?


Relevant equations: Fspring=kx Espring=1/2kx^2



My attempt: Fnet=mg-kx I am getting 26.452 but the answer for part a) is 0.962 down and 3.33ms/^2
 
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Hi Physicsdb. Welcome to Physics Forums.

Show us your work for how you arrived at the number 26.452. Also, what are its units?
 
i figured to find the net force it would be the force of gravity minus the force of the string,
Fnet=Fg-Fs
Fnet=mg-kx
Fnet=2.89kg(9.8m/s^2)-(18.7N/m)(0.1m)
Fnet=28.322-1.87
Fnet=26.452 N
 
physicsdb said:
i figured to find the net force it would be the force of gravity minus the force of the string,
Fnet=Fg-Fs
Fnet=mg-kx
Fnet=2.89kg(9.8m/s^2)-(18.7N/m)(0.1m)
Fnet=28.322-1.87
Fnet=26.452 N
That should be 0.289 kg.
 

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