Finding the inertia with a thin rectangular sheet

AI Thread Summary
The discussion focuses on calculating the moment of inertia for a thin rectangular sheet of metal with mass M and sides a and b. For part A, the correct formula for the moment of inertia about an axis parallel to side b is M(a^2)/12, as the variable b does not factor into the final answer. Part B requires finding the moment of inertia for an axis perpendicular to the one in part A, but confusion from part A led to a lack of attempts at this part. Participants expressed frustration over the clarity of the guidance received, with one user ultimately resolving their confusion independently. The conversation highlights the importance of showing work and reasoning in physics problem-solving.
kgianqu2
Messages
16
Reaction score
0
A) A thin, rectangular sheet of metal has mass M and sides of length a and b. Find the moment of inertia of this sheet about an axis that lies in the plane of the plate, passes through the center of the plate, and is parallel to the side with length b.
Express your answer in terms of given quantities.

attempt at answer: M(a^2+b^2)/12 (mastering physics said the correct answer does not depend on the variable b)

B) Find the moment of inertia of the plate for an axis that lies in the plane of the plate, passes through the center of the plate, and is perpendicular to the axis in part A.
Express your answer in terms of given quantities.

I did not attempt an answer on this part because of the confusion in part A.

Please help, I am very confused about how to input this into mastering physics.
 
Physics news on Phys.org
kgianqu2 said:
A) A thin, rectangular sheet of metal has mass M and sides of length a and b. Find the moment of inertia of this sheet about an axis that lies in the plane of the plate, passes through the center of the plate, and is parallel to the side with length b.
Express your answer in terms of given quantities.

attempt at answer: M(a^2+b^2)/12 (mastering physics said the correct answer does not depend on the variable b)
That's the moment of inertia about the axis through the center of mass and perpendicular to the sheet.
B) Find the moment of inertia of the plate for an axis that lies in the plane of the plate, passes through the center of the plate, and is perpendicular to the axis in part A.
Express your answer in terms of given quantities.

I did not attempt an answer on this part because of the confusion in part A.

Please help, I am very confused about how to input this into mastering physics.

For part A), think of the sheet as being broken up into thin strips of length a and width Δx .

By the way, you really didn't show your work. You just gave an answer without giving the reasoning behind it.
 
You honestly didn't help at all. I figured it out on my own, thanks a lot. The worst help ever. The answer that I had was basically right, I just had to take out the variable b for the first part, and a for the second part. But thanks for asking where I got the equation from.
 
kgianqu2 said:
You honestly didn't help at all. I figured it out on my own, thanks a lot. The worst help ever. The answer that I had was basically right, I just had to take out the variable b for the first part, and a for the second part. But thanks for asking where I got the equation from.
I glad to have helped.
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

Finding the Moment of Inertia for a Rectangular Sheet
Replies
1
Views
4K
Correct Use of the Parallel Axis Theorem for Moment of Inertia
Replies
2
Views
2K
How Do You Calculate the Moment of Inertia for a Rectangular Sheet?
Replies
1
Views
10K
Moments of inertia of a rectangular plate
Replies
5
Views
5K
I Thought I Understood Gauss' Law (Sheets)
Replies
26
Views
2K
Angular Momentum Problem: Mouse walking on a rotating turntable
Replies
5
Views
1K
Distance between 2 axis in Parallel Axis Theorem
Replies
5
Views
2K
Moment of Inertia of a Rotating Disk
Replies
1
Views
2K
Moment of inertia of a rod bent into a square
Replies
12
Views
2K
How do calculate this moment of inertia?
Replies
3
Views
1K

Hot Threads

Recent Insights

Back
Top