Megha S.

asked • 09/12/15

Two bodies of masses m1 and m2 fall from height h1 and h2 respectively.The ratio of their velocities,when they hit the ground is?


options are
under root h1/h2
h1/h2
m1h1/m2h2
h1^2/h2^2

1 Expert Answer

By:

Alexander B. answered • 09/12/15

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Hello Megha,
 
Correct answer is: √(h1/h2)
Masses m1 and m2 are immaterial to the solution of this particular problem. Here a simple explanation:
 
h1=(1/2)gt12
h2=(1/2)gt22

V1=gt1
v2=gt2

V1/V2 = t1/t2 = √(h1/h2)
 
Hope this will help.
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Megha S.

Explain?
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09/12/15

Alexander B.

Please see my extended answer. Best regards,
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09/12/15

Megha S.

Why are masses immaterial for this question.please help
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09/13/15

Megha S.

And how did you get h1=1/2gt1^2
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09/13/15

Alexander B.

It's a well-known free fall equation (mass is not included because all physical bodies conform to the same equations).
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09/13/15

Megha S.

the masses here arent included cause it obeys the free fall equation? I didnt get you? 
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09/13/15

Alexander B.

They accelerates at the same rate (namely g) regardless of the actual masses. Take a look at the equation of free fall: h1=1/2gt1^2 - mass, obviously, is irrelevant for this particular problem.
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09/13/15

Megha S.

Thank you sooo muchhhh :)
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09/14/15

Megha S.

so basically we are considering both the masses to be of equal weight and we consider that its   A free fall as nothing is mentioned in the question?
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09/14/15

Alexander B.

You are welcome.
1. The problem definition stated: "Two bodies of masses m1 and m2 fall from height h1 and h2" - the fall actually means a free fall, and so are the corresponding equations.
2. No, we DO NOT consider masses to be equal. They just ACCELERATES with the same rate (namely: Gravitational Acceleration g) regardless of their actual masses. I would recommend you to read some tutorials on this topic - there are plenty resources online.
Best regards,
 
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09/14/15

Megha S.

Ohk i got it.But why isnt mass included in the free fall equation?
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09/14/15

Alexander B.

You do not need to know the mass for this particular calculation: the velocity at the ground level depends just on heights because the acceleration (g) is a constant value for any physical body of any mass. I recommend you to do some reading on this subject (free fall equations). Best regards,
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09/14/15

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