Any tangential velocity greater than zero results in a **radial acceleration** greater than zero. As a result, the only possibility for radial acceleration to equal zero is for it to be equal to zero.

- Is it possible to have a zero tangential and a nonzero centripetal acceleration?
- Why is tangential acceleration zero?
- Is acceleration zero in uniform circular motion?
- Are radial and normal acceleration the same?
- Can you move with zero acceleration?
- What is the value of tangential acceleration in non-UCM?

Because the acceleration is directed towards the center of the circle, the tangential component of acceleration in a uniform circular motion is zero. This is known as **centripetal acceleration**, and it results from a change in velocity direction while the magnitude of the velocity stays constant. If the object causing the movement is also moving in a straight line away from the center, then there is no tangential acceleration.

As a result of the constant angular velocity, tangential acceleration is zero during uniform circular motion. It should be noted that the tangential acceleration is 0 during uniform circular motion since the angular velocity is constant. However, due to the nature of physics, the object still experiences an upward force due to gravity. This is why objects in **uniform circular motion experience** no change in their altitude.

Acceleration in Radial and Tangential Directions Because radial acceleration is always normal to instantaneous velocity, it is sometimes referred to as normal acceleration. Tangential acceleration has a magnitude equal to the rate of change of the particle's speed with respect to time and is always tangential to the route. Thus, it can be viewed as a component of velocity that points in the direction of displacement from **a fixed point**.

Yes. There is no change in velocity when there is no acceleration. Constant velocity denotes constant speed and direction since velocity encompasses **both speed** and direction (i.e., straight-line motion).

(ii) Non-uniform circular motion: In this type of motion, the body's rotational speed changes, i.e., the direction of rotation changes at every moment and the magnitude of the rotational speed also changes; thus, the value of tangential acceleration is non-zero because the magnitude of the angular momentum changes significantly. The body will continue in this motion as long as there is energy available for its maintenance (i.e., it is not accelerated by an external force). One example is a child's swing. If the child lets go of the rope, the rope will continue to rotate until some internal source of energy is exhausted.

In general, if there is no external force acting on the body, then it will continue in **uniform circular motion** unless energy is supplied to it from outside. Thus, the tangential component of acceleration of a particle in uniform circular motion is zero.

However, if the particle is subjected to **an external force** that causes it to accelerate in a circle, then the tangential component of **its acceleration** will not be zero even though there is no change in the particle's velocity vector. For example, if a balloon is blown by wind into a circle, then the tangential component of its acceleration is non-zero even though there is no change in its velocity vector.