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

[fball558]

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

 

[fball558]

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.

 

[nlightner]

Based on the information provided, it seems like you have already calculated the translational kinetic energy (Ktrans) and the rotational kinetic energy (Krot) of the system. To find the total kinetic energy (Ktotal), you will need to add these two values together.

Ktotal = Ktrans + Krot

To find the distance through which the gravitational force acts on the system, you can use the formula for work (W = F * d) and solve for d.

d = Wgrav / Fgrav

Where Fgrav is the gravitational force acting on the system, which can be calculated using Newton's Law of Gravitation (Fgrav = G * m1 * m2 / r^2).

To find the work done by your hand on the system (Whand), you can use the same formula (W = F * d) and solve for d, where F is the force applied by your hand and d is the distance through which your hand moves.

Now, to find the total energy of the system, you can use the conservation of energy equation:

delta(E) = W + Q

Since there is no heat transfer (Q = 0), the equation simplifies to:

delta(E) = W

So, the total energy of the system (E) would be the sum of all the work done on the system (W) by different forces. In this case, it would be the work done by the gravitational force (Wgrav) and the work done by your hand (Whand).

E = Wgrav + Whand

I hope this helps! Let me know if you have any further questions.