Question

The angular acceleration of a body, moving along the circumference of a circle, is:

• A. along the axis of rotation
• B. along the radius, away from center
• C. along the radius towards the centre
• D. along the tangent to its position

Answer 1

Answer: (D)

along the tangent to its position

Answer 2

The correct option is (D): along the tangent to its position

Angular acceleration is due to Torque. Suppose there is a plane of a circle, and the body is moving along with the circumference of a circle.

Torque, τ = I x α

I = moment of inertia

and the angular direction is towards the direction of the Torque.

and, the direction of the Torque is, τ = r × F

Where r is the radius and F is the perpendicular tangent.

and the direction of torque is perpendicular to r and perpendicular to F. r and F lie perpendicular to the circle. If the two vectors lie in a circle of a plane, then the cross product of two vectors lies on the perpendicular. And, if the torque lies on the perpendicular of the plane, then the angular acceleration will also lie on the perpendicular of the plane. Hence the correct answer is option D, long the tangent to its position.