Total Energy Help: Ktrans, Wgrav, Whand, Ktotal & Krot

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SUMMARY

The discussion revolves around calculating various forms of energy in a mechanical system, specifically focusing on translational kinetic energy (Ktrans = 10.412 J), gravitational work (Wgrav = -16.758 J), and work done by a hand (Whand = 102.96 J). The user attempts to apply the conservation of energy principle, stating that total energy (delta(E)) equals the work done by the hand plus the work done by gravity. However, the user encounters discrepancies in their calculations for total kinetic energy and rotational kinetic energy, indicating a need for further clarification on these concepts.

PREREQUISITES
  • Understanding of kinetic energy concepts, specifically translational and rotational kinetic energy.
  • Familiarity with the work-energy principle in physics.
  • Knowledge of gravitational potential energy calculations (mgh).
  • Basic grasp of conservation of energy principles.
NEXT STEPS
  • Review the principles of conservation of energy in mechanical systems.
  • Study the calculations for rotational kinetic energy and its application in real systems.
  • Learn about the work-energy theorem and its implications in physics problems.
  • Explore the effects of friction and heat transfer on energy calculations in mechanical systems.
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Students studying physics, particularly those focusing on mechanics, energy calculations, and problem-solving in multi-part energy-related assignments.

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Homework Statement



it is a multi part problem i found most just need help on last two but gave answers to the ones i found because they are needed to determin the answer.

What is the translational kinetic energy of the real system, at the instant shown in the right diagram?
Ktrans = 10.412 J

What is the distance through which the gravitational force acts on the real system? .19 m

How much work is done on the system by the gravitational force?
Wgrav = -16.758 J

What is the distance through which your hand moves? .72 m

How much work do you do on the real system?
Whand = 102.96 J

At the instant shown in the right diagram, what is the total kinetic energy of the real system?
Ktotal = J

What is the rotational kinetic energy of the machinery inside the box?
Krot,f = J

Homework Equations


from a question earlier on my assingment i found that only
translational and rotational kenetic energy are pressent
will need conservation of energy
delta(E) = W + Q
i assumed Q = 0 because we have not went in depth about heat trasfer due to friction and all that stuff.

The Attempt at a Solution

 
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oops i forgot to show my work ok here is what i did.
inital state box has no energy it is on the ground and not moving.
final state it is .19 meters above the ground moving in +y direction and spinning

i took delta(E) = w + Q Q=0
so delta(E) = W
W would equal work done by your hand (102.96) plus work done by gravity (-16.758) since gravity is - it is actually suptracting so i get delta(E) = 86.202
that sould be total energy but we only want kenetic energy so i found potential energy using mgh (mass was given as 9 kg) so 9*9.8*.19 = 16.758. that should be potential so
i subtracted that from total 86.202 - 16.758 = 69.444
that is my answer but it says I am wrong. any help would be great!
thanks and sorry about the length of this post.
 

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