Square Hole, Exploding Shell, Rotating Molecule, and Atwood's Machine

In summary, the conversation covers a variety of physics problems, including finding the center-of-mass of a missing piece of a square plate, calculating the angular velocity of an oxygen molecule, and determining the change in potential energy of an Atwood's machine system. The main strategies discussed include using conservation laws, such as conservation of energy and momentum, and understanding the relationship between rotational inertia and kinetic energy.
  • #1
quidditch
1
0
1. A uniform square plate 7.2 m on a side has had a square piece 3.9 m on a side cut out of it. The center of the missing piece is at x = 1.65 m, y = 0. The center of the square plate is at x = y = 0. What is the x-coordinate of the center-of-mass of the remaining piece? 2. http://www.ottisoft.com/samplact/ImageM35.gif 3. I really don't know what to do. I know that the square piece that was cut out needs to be subtracted, but that's all I can figure out.

1. A shell is fired from a gun with a muzzle velocity of 52.0 m/s, at an angle of 32.0 degrees with the horizontal. At the top of the trajectory, the shell explodes into two fragments of equal mass. One fragment, whose speed immediately after the explosion is zero, falls vertically. How far from the gun does the other fragment land, assuming level terrain and negligible air drag? 2. http://capa8.phy.ohiou.edu/res/ohiou/OUp250lib/pictures/shell_explode1.jpg3. I really have absolutely no idea where to even begin. I always have problems with finding the equations to use.

1. The oxygen molecule, O2, has a total mass of 5.30×10-26 kg and a rotational inertia of 1.94×10-46 kg-m2 about an axis perpendicular to the center of the line joining the atoms. Suppose that such a molecule in a gas has a speed of 1.52×103 m/s and that its rotational kinetic energy is two-thirds (2/3) of its translational kinetic energy.
Find its angular velocity.
2. Again, I have no clue what to do for this problem!

1. In an Atwood's machine, one block has a mass of 540.0 g, and the other a mass of 695.0 g. The pulley, which is mounted in horizontal frictionless bearings, has a radius of 5.10 cm. When released from rest, the heavier block is observed to fall 86.2 cm in 2.64 s (without the string slipping on the pulley).
What is the change in the potential energy of the system after 2.64 s?
2. There are seven parts to this problem and I did get the first six right:

What is the acceleration of the 540.0-g block? 2.4700×10-1 m/s^2
What is the acceleration of the 695.0-g block? 2.4700×10-1 m/s^2
What is the tension in the part of the cord that supports the 540.0-g block? 5.4308 N
What is the tension in the part of the cord that supports the 695.0-g block? 6.6463 N
What is the angular acceleration of the pulley? 4.8430
What is the rotational inertia of the pulley? 1.2800×10-2 kg*m^2

But now i can't figure out how to do the last one, which is the change in potential energy of the system.


I am pretty sure I can figure these out if I have the correct equations, I just can never seem to use the right ones. So even the littlest thing might help. Thanks so much!
 
Last edited by a moderator:
Physics news on Phys.org
  • #2
Welcome to PF!

Hi quidditch! Welcome to PF! :smile:

1. How would you solve it if there was no hole, but an extra square plate was added?

ok, use the same method, but with negative mass. :wink:

2. Use conservation of energy to find the height, and then conservation of momentum to find the initial velocity.

3. How is rotational inertia related to rotational kinetic energy?
 

1. What is a square hole?

A square hole is a geometric shape with four equal sides and four right angles. It is a two-dimensional representation of a cube.

2. How does an exploding shell work?

An exploding shell is a type of explosive projectile that is typically fired from a cannon or other artillery weapon. The explosion is caused by a chemical reaction between the explosive material inside the shell and a fuse that is lit upon firing. As the shell travels through the air, the fuse burns down until it reaches the explosive material, causing it to detonate and release energy in the form of an explosion.

3. What is a rotating molecule?

A rotating molecule is a molecule that is constantly spinning or rotating. This rotation can occur in different ways, such as around a central axis or in a more complex motion. The rotation of molecules is an important factor in understanding their properties and behaviors.

4. How does Atwood's Machine work?

Atwood's Machine is a simple physics experiment that involves a pulley, a string, and two masses. The masses are connected by the string and one is heavier than the other. When the system is released, the heavier mass will accelerate downwards while the lighter mass accelerates upwards, demonstrating the principles of gravity and acceleration.

5. What are the applications of the Square Hole, Exploding Shell, Rotating Molecule, and Atwood's Machine?

The Square Hole, Exploding Shell, Rotating Molecule, and Atwood's Machine have various applications in different fields. For example, the square hole can be used in construction and design. The exploding shell has military and industrial uses. Rotating molecules are important in chemistry and can help us understand the behavior of materials. Atwood's Machine is commonly used in physics experiments and can also be used to demonstrate the principles of simple machines.

Similar threads

Replies
2
Views
2K
  • Introductory Physics Homework Help
Replies
13
Views
1K
  • Introductory Physics Homework Help
Replies
8
Views
588
  • Introductory Physics Homework Help
Replies
15
Views
1K
Replies
2
Views
1K
  • Advanced Physics Homework Help
Replies
8
Views
9K
  • Advanced Physics Homework Help
2
Replies
36
Views
2K
  • Introductory Physics Homework Help
Replies
3
Views
1K
Replies
5
Views
2K
  • Introductory Physics Homework Help
Replies
16
Views
1K
Back
Top