Newton's Second Law finding value of force problem

AI Thread Summary
To determine the force exerted by a soccer ball of mass 0.5 kg kicked at 14 m/s upon hitting a rock for 0.18 seconds, the momentum and time relationship is used. The momentum is calculated as 0.5 kg multiplied by 14 m/s, resulting in 7 kg·m/s. The force is then found by dividing the momentum by the time of contact, yielding approximately 38.9 N. It is clarified that force represents the change in momentum per unit time, which aligns with the scenario since the ball's velocity becomes zero upon impact. This approach effectively solves the problem using the principles of Newton's Second Law.
goomer
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Homework Statement



If a soccer ball of mass 0.5 kg is kicked with a speed of 14 m/s and hits a rock and is in contact with it for 0.18 seconds, with what force will it hit?

Homework Equations



Fnet = ma

The Attempt at a Solution



I have no idea what to do to get the acceleration for the above formula. It can't possibly be just 14/0.18 can it?
 
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Force can also be defined in terms of momentum and time. What is it, and can you use that in this problem?
 
Oh I see, so:

Force = Momentum/Time

Momentum = Mass * Velocity = 0.5 kg * 14 m/s = 7

Force = 7/0.18 s = 38.9N right?
 
goomer said:
Oh I see, so:

Force = Momentum/Time

Momentum = Mass * Velocity = 0.5 kg * 14 m/s = 7

Force = 7/0.18 s = 38.9N right?

Yep! :approve:

Force is actually the change in momentum per unit time. But since the ball was in contact with the stone for that time, and its velocity was zero then, your equation worked out.
 
Thank you so much for your help!
 

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