Volume of a Spherical Raindrop: Differential Equation Solution

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In summary, the formula for calculating the volume of a spherical raindrop is V=4/3πr^3, and the differential equation for this volume is derived using the chain rule of differentiation. This equation allows for a more accurate prediction of the final volume of the raindrop by taking into account factors such as evaporation and surface tension. However, it can only be applied to spherical raindrops and not other types. The volume of a spherical raindrop changes over time due to evaporation and surface tension, with the exact rate depending on various factors.
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Homework Statement



A spherical raindrop evaporates at a rate proportional to its surface area. Write a differential equation for the volume of the raindrop as a function of time.

Homework Equations



V = (4/3)πr3
S=4πr2

The Attempt at a Solution



dV/dt = -k(4πr2), k>0

Therefore dV/dt = -k(3/r)V

But the answer in the back of the book is

-kV2/3

How did they get that?
 
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in your solution, write r in terms of V and then absorb other constants in k.
 

FAQ: Volume of a Spherical Raindrop: Differential Equation Solution

What is the formula for calculating the volume of a spherical raindrop?

The formula for calculating the volume of a spherical raindrop is V=4/3πr^3, where V is the volume and r is the radius of the raindrop.

How is the differential equation for the volume of a spherical raindrop derived?

The differential equation for the volume of a spherical raindrop is derived from the relation between the volume of a sphere and its radius, using the chain rule of differentiation. This equation is then solved using integration techniques to obtain the final solution.

What is the significance of using a differential equation to solve for the volume of a spherical raindrop?

Using a differential equation allows us to model the changing volume of a raindrop over time, taking into account factors such as evaporation and surface tension. This gives a more accurate prediction of the final volume of the raindrop compared to using a simple formula.

Can the differential equation solution for the volume of a spherical raindrop be used for any type of raindrop?

No, the solution is specifically for spherical raindrops. The volume of other types of raindrops may be calculated using different equations or models.

How does the volume of a spherical raindrop change over time?

The volume of a spherical raindrop decreases over time due to evaporation and increases due to surface tension. The exact rate of change depends on the size and composition of the raindrop, as well as environmental factors such as temperature and humidity.

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