- #1
TheDemx27
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Homework Statement
We are trying to find out whether we can hit a weight ##m=3## kg up to a given ##h=15.24## meters with a hammer with a head of ##m=6## kg swung at ##v=10## m/s.
Homework Equations
KE=0.5mv^2
PE=mgh
p=mv
The Attempt at a Solution
One solution is to even see if the energy put into the system is equal to the energy needed to get to our ##h##. For the energy put into the system, we have 0.5*6*10^2=300 joules. The energy required to attain a potential energy large enough for an ##h=15.24## is 3*9.8*15.24=448. Since our energy put into the system is not enough to raise the weight up to our required ##h##, we conclude no, we cannot raise the weight to the required height.
Another way to do it, conservation of momentum. The weight's velocity due to the hammer is 6*10/3, and the distance it will travel is ##v^2/(2*a)=s##=20^2/(2*9.8)=20.4>15.24. So now we would say that we can raise the weight to the required height.
Which way is correct?