
#1
Feb708, 10:23 PM

P: 4

A ball of mass .5 kg is dropped from a height of 5 m. What is the greatest velocity it will have just before hitting the ground?
vf squared = vi squared + 2ad vf squared = 0 squared + 2(9.8)(5) vf = 9.8 m/s So the greatest velocity is 9.8 m/s, right? I am still very confuzzled and I think this is the right answer because where did the mass go? Or it doesn't even matter? Can someone verify? Thanks! 



#2
Feb708, 10:55 PM

HW Helper
P: 4,442

Yes. Mass does not matter in the free fall under gravity. All the body get accelerated equally.




#3
Feb708, 10:57 PM

Sci Advisor
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P: 25,167

Welcome to the forums! No, mass doesn't matter. The acceleration downwards is g, independent of mass, ask Galileo. It's a purely kinematical problem.




#4
Feb708, 11:00 PM

P: 4

Mass and free fall question
Thanks! So is my answer correct?




#5
Feb708, 11:07 PM

Sci Advisor
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P: 25,167

Approximately, yes. I would round the answer to 9.9m/sec. But that's a detail.




#6
Feb708, 11:08 PM

P: 4

Sweet! Thanks!




#7
Feb708, 11:14 PM

P: 4

I don't know why the question had mass in it. Trick question or something haha.




#8
Feb708, 11:29 PM

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P: 25,167

In real world problems YOU have to figure out what's important and what isn't. It's just practice.



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