Question

A particle moving along a circular path due to a centripetal force having constant magnitude is an example of motion with:
A) Constant speed and velocity
B) Variable speed and velocity
C) Variable speed and constant velocity
D) Constant speed and variable velocity

Answer 1

Hint: Speed of a particle is defined as the magnitude of the change of the position of the particle. Since it involves only magnitude, so it is a scalar quantity. But velocity is defined as the rate of change of position with respect to time in a particular direction. It is written as the ratio of displacement of the particle and time. It has both magnitude and direction so it is a vector quantity.

Complete answer:
If a particle is moving along a circular path then centripetal force will act on it. The distance travelled by a particle in a particular interval of time, is expressed in terms of average speed. Since it is given that the magnitude of the particle is constant, this means that the speed of the particle is constant, but the velocity is changing as direction is also changing.
So, this is an example of particles moving with constant speed and variable velocity.

Hence, Option D is the right answer.

Note: It is important to note that the speed or the velocity of a particle is defined as whether the particle is moving fast or slow. If the velocity of the particle also changes with time, then the particle is said to be accelerating. If an object slides over an inclined plane or a horizontal surface that has low friction, then it is said to have constant velocity. Any particle that is moving with constant velocity is the simplest type of motion to study.