Rotational Dynamics, 1.68(SS.Krotov) and 1.264(Irodov)

In summary, the conversation discusses two different problems involving energy conservation and the use of equations to solve for unknown values. The moments of inertia are different in the two problems, and one solution ignores rotational kinetic energy completely. The first problem involves a solid cylinder and a disk with the same moments of inertia, while the second problem involves light wheels on a heavy axle. There may be a difference in questions between the two problems.
  • #1
Shridhar
2
0

Homework Statement


I have attatched both the problems. The figure is essentially the same.

Homework Equations


1. Energy conservation
2.mgcosx - N = mv^2/r , where N is zero in limiting case.

The Attempt at a Solution


I solved the whole question and got the answer given in irodov(0.33 gR(7cosx-4))^1/2 .
But answer given in krotov is different.
So, there must be a difference in questions but i am unable to grasp it.
Thanks in advance.
 

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  • #2
Shridhar said:
there must be a difference in questions
The moments of inertia are different.
 
  • #3
haruspex said:
The moments of inertia are different.
Well, in the detailed answer Krotov has ignored Kinetic energy due to rotational motion completely.His final equation is
mv^2/2 = mV^2/2 - mgr(1-cosx).
Anyways, moment of inertia of solid cylinder and disk are same
 

Attachments

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FAQ: Rotational Dynamics, 1.68(SS.Krotov) and 1.264(Irodov)

1. What is rotational dynamics?

Rotational dynamics is a branch of physics that deals with the motion of objects that are rotating or spinning around a fixed axis. It involves the study of forces, torques, and angular motion.

2. What is the significance of the numbers 1.68 (SS.Krotov) and 1.264 (Irodov) in rotational dynamics?

1.68 and 1.264 are numerical values that represent the coefficients of inertia for different objects in rotational dynamics. These values are used in equations to calculate the moment of inertia, which is a measure of an object's resistance to rotational motion.

3. How are rotational dynamics and linear dynamics related?

Rotational dynamics and linear dynamics are closely related as they both involve the study of motion and forces acting on objects. However, they differ in that rotational dynamics deals with objects that are rotating, while linear dynamics deals with objects that are moving in a straight line.

4. What are some real-life applications of rotational dynamics?

Rotational dynamics has many practical applications, such as in the design of machines and vehicles that involve rotating parts, such as engines, turbines, and propellers. It is also used in sports, such as figure skating and gymnastics, to understand and improve the performance of rotational movements.

5. How can I apply the principles of rotational dynamics in my daily life?

While it may not be obvious, rotational dynamics plays a role in our daily lives. For example, when riding a bicycle, the rotation of the wheels and pedals is governed by principles of rotational dynamics. Similarly, when throwing a ball or swinging a bat, the motion of the object is influenced by rotational dynamics. Understanding these principles can help improve our skills in various activities and tasks.

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