Calculating Momentum of a Falling Mass: 30.00 kg Object from 4.00m Height

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To calculate the momentum of a 30.00 kg mass falling from a height of 4.00 m, the velocity just before impact is needed. Two methods are suggested: using kinematic equations to find velocity by solving for time with x = 1/2 gt², or applying energy conservation principles where kinetic energy equals potential energy. By equating kinetic energy to potential energy, one can derive momentum directly. The discussion highlights the importance of understanding both kinematic equations and energy conservation in solving for momentum. This approach effectively aids in determining the mass's momentum just before it hits the ground.
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Homework Statement


A 30.00 kg mass falls from a height of 4.00m. The momentum of the mass just before it hits the ground is?


Homework Equations



obviously p=mv

The Attempt at a Solution



I just can't figure out how to get a velocity for this formula?
 
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ckaiser813 said:

Homework Statement


A 30.00 kg mass falls from a height of 4.00m. The momentum of the mass just before it hits the ground is?

Homework Equations



obviously p=mv

The Attempt at a Solution



I just can't figure out how to get a velocity for this formula?

Consider one of these kinematic equations:
https://www.physicsforums.com/showpost.php?p=905663&postcount=2
 
There are 2 ways to do this.

1) Find the velocity using kinematic equations:
x = \frac{1}{2}gt^2
you know x and g so you can solve for t. After solving for t you can get the velocity from v=gt.

2) You can also use energy conservation
KE=\frac{1}{2}mv^2=PE=mgh
and then applying the knowledge of what KE is and momentum is
KE=\frac{p^2}{2m}
to find p directly.
 
yes sir that helped me figure out what the book got, thanks a bunch!
 
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