Melting a snowball by throwing it at a wall

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Homework Help Overview

The discussion revolves around a physics problem involving the melting of a snowball upon impact with a wall. The original poster seeks to determine the necessary speed to achieve complete melting, using concepts from thermodynamics and kinetic energy.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants explore the relationship between the energy required to melt the snowball and the kinetic energy of the snowball. Questions arise regarding the necessity of mass in the equations used, with some suggesting that mass cancels out.

Discussion Status

Some participants have provided insights that led to a reevaluation of the original equations. The discussion has progressed with attempts to simplify the problem, and there is an indication of further calculations being made based on the revised understanding.

Contextual Notes

There is a lack of specific information regarding the mass of the snowball, which has been a point of confusion. Participants are navigating this uncertainty while attempting to solve the problem.

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Homework Statement



You throw a snowball at 0.0 Celsius at a brick wall. If you want it to melt completely, how fast will you have to throw it?

Homework Equations



Q = mL

E_k = \frac{1}{2} mv^2

The Attempt at a Solution



I initially reasoned that you would use Q = mL to find the energy needed to melt it and then substitute that into the Kinetic energy formula, giving:

mL = \frac{1}{2} mv^2

However, I am given no information regarding the mass of the snowball and haven't figured out a method to find that mass.
Any suggestions?

Thanks,
 
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Why do you need mass when it cancels out in the equation you formed? :confused:
 
AbsoluteZer0 said:

Homework Statement



You throw a snowball at 0.0 Celsius at a brick wall. If you want it to melt completely, how fast will you have to throw it?

Homework Equations



Q = mL

E_k = \frac{1}{2} mv^2

The Attempt at a Solution



I initially reasoned that you would use Q = mL to find the energy needed to melt it and then substitute that into the Kinetic energy formula, giving:

mL = \frac{1}{2} mv^2

However, I am given no information regarding the mass of the snowball and haven't figured out a method to find that mass.
Any suggestions?

Thanks,

Just assume that mass equals 1.
 
Pranav-Arora said:
Why do you need mass when it cancels out in the equation you formed? :confused:

Ah!
I didn't notice that. Thanks.

I'm now at

L = \frac{1}{2}v^2

Edit:

I changed 334 j/g to 334000 j/kg and arrived at around 800 m/s
 
Last edited:
If you want your working checked, please post it.
 

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