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Ek = Eg question

  • Thread starter jaron
  • Start date
  • #1
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Homework Statement


you throw a ball directly upward, giving it an initial velocity of 10.0 m/s. neglecting friction, what would be the maximum height of the ball? (explain why you do not need to know the mass of the ball)



Homework Equations


now the problem itself i understand.

we need Eg=mgh, Ek=1/2mv^2



The Attempt at a Solution


Ek=Eg
1/2mv^2 = mgh
1/2v^2 = gh
1/2(10.0)^2 = 9.81h
50/9.81 = h
h = 5.1m

i understand that we do not have mass and so it must cancel out, but i am confused as to why we do not need to know the mass?
 

Answers and Replies

  • #2
Cyosis
Homework Helper
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What falls faster a feather or a cannon ball? (this problem assumes 0 resistance)
 
  • #3
23
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neglecting air friction, neither..
meaning mass doesnt matter
 
  • #4
Cyosis
Homework Helper
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So you're saying that gravity accelerates all masses in an equal manner. This is correct. What is the one force acting upon the ball after you release it?
 
  • #5
23
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only gravity (in this instance because it says to neglect friction)
 
  • #6
Cyosis
Homework Helper
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Yes, do you understand now why you don't need to know the mass of the ball?
 
  • #7
23
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i understand.
thank you
 

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