Question

Identify the correct statement for the rotational motion of a rigid body \(\\{A\\}\) Individual particles of the body do not undergo accelerated motion \\{B \\} The centre of mass of the body remains unchanged. \\{C\\} The centre of mass of the body moves uniformly in a circular path \\{D\\} Individual particle and centre of mass of the body undergo an accelerated motion.

Short answer

The correct statement for the rotational motion of a rigid body is \(D: \textrm{Individual particle and centre of mass of the body undergo an accelerated motion}\).

Step-by-step solution

Identify the Key Concepts

The first step to solve this exercise is to recall the basics of rotational motion of a rigid body. A rigid body is an object with a shape that does not change. In rotational motion, every particle of the body moves in a circular path about a line. This line, also called the axis of rotation, penetrates the body. Contrary to translational motion, particles in a rigid body do not all have the same velocity or acceleration.

Evaluate Statement A

For a rigid body in rotational motion, all particles move about the axis in circular paths. This means that these particles are undergoing an accelerated motion, given the constant change of the motion direction. Remember that acceleration is defined as any change in the velocity of an object, which includes both magnitude and direction changes. Therefore, statement A is incorrect.

Evaluate Statement B

The center of mass of a rigid body in rotation does not necessarily remain unchanged. It depends on the type of rotation. In cases of pure rotation, the center of mass is fixed, but in cases of rolling or general plane motion, for example, the center of mass can change its position over time. Therefore, statement B can be true in some circumstances, but not in all. It is a partially correct statement.

Evaluate Statement C

Regarding statement C, It is also not a universally true statement. The center of mass of a rotating body does not always move uniformly in a circular path. As before, this depends on the specific type of rotational motion in question. Thus, statement C is also partially correct.

Evaluate Statement D

Finally, let's consider statement D. In rotational motion, every particle of the rigid body indeed moves in a circular path about a line, meaning both the individual particle and the centre of mass of the body undergo an accelerated motion, because their direction is continuously changing. Therefore, statement D is correct. So, the correct statement for the rotational motion of a rigid body is "D: Individual particle and centre of mass of the body undergo an accelerated motion."