Find the acceleration in terms of velocity and displacement

1. Nov 9, 2009

semc

Assume a raindrop falls from the clouds and the mass increases as it falls and the increase in mass is 3kg/m. Neglecting any frictional force, find the acceleration in terms of velocity and displacement. Initially when t=0 assume mass is negligible.

I just want to ask if we were to neglect drag or air resist, shouldn't the acceleration be g?

2. Nov 9, 2009

willem2

Re: Raindrops

It increases in mass by colliding with water (in some form) that isn't moving. That will slow it down. Is the increase 3kg/m? That doesn't make sense at all. You'd think it would depend on the size of the raindrop, and that the effect would be 10^4 to10^5 times smaller.

3. Nov 9, 2009

redargon

Re: Raindrops

Yes, I would think so. Could this be a trick question to test your understanding? if so, I think you understand it :)

If we really wanted to go overboard we could calculate the value of g for different altitudes, but it should be relatively negligible.

Just a quick reality check, is the increase in mass of 3kg/m reasonable? If it fell 100m, it would gain 300kg, that's a pretty heavy raindrop.