Conservation of momentum query

AI Thread Summary
The discussion centers on using conservation of momentum to determine the initial velocity of a ball affected by wind. It highlights the equation m_air * v_air = m_ball * v_ball, suggesting that v_ball can be calculated if m_air and v_air are known. However, participants point out that m_air cannot be definitively assigned a value without specific system details. The air's varying speeds complicate the calculation, making it impossible to accurately track total momentum. Ultimately, the consensus is that the initial velocity of the ball cannot be determined solely through conservation of momentum.
volican
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I have a ball and the wind blows on it. Could I find the initial velocity of the ball from conservation of momentum?

m_air * v_air = m_ball * v_ball

v_ball = (m_air * v_air) / m_ball

What would you put for m_air?
 
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The initial speed?
That can be anything, you cannot calculate it unless you know something about your system.

The final speed? You can find the speed where the ball is in a force equilibrium. The ball will approach this speed over time.
volican said:
Could I find the initial velocity of the ball from conservation of momentum?
No. The air won't all move at the same speed, and you cannot properly keep track of its total momentum.
 
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