Question

Is kinetic energy constant in circular motion?

Answer 1

Hint: When attempting questions both based on kinetic energy and circular motion like the question given to us above, keep in mind the various factors and terms related to both of them, and know the effects of the factors in increasing or decreasing the kinetic energy during circular motion.

Complete step by step answer:
Any motion to be classified into circular motion, it is necessary for the object to move in a specific way so that the distance of the object from the center point always remains the same. Roughly speaking if any object is moving roughly on a circular path it is termed as circular motion. The speed of the object in motion may or may not change, but because the magnitude of direction changes at every point of time, the velocity will never be the same at two consecutive points. There are many examples of circular motion in our lives, like artificial satellites orbiting the earth, stones tied to a rope and swung in circles, cars on a curved race track et cetera.
When the object in circular motion is moving with constant speed – again speed not velocity because velocity cannot be constant in circular motion – the motion is termed to be called uniform circular motion. As the object in motion is constantly changing directions, it can mean that the object that is forming a circle on the path will complete full strips around the same path in the same amount of time each time, that is the time period will remain constant.
Now seeing that the speed is constant in uniform circular motion, and we know the mass is also taken constant, and keeping in mind the equation for Kinetic energy \[\dfrac{1}{2}m{v^2}\]
As a result, in uniform circular motion, the kinetic energy will remain constant. But keep in mind it is only for uniform circular motion, and not in uniform circular motion.

Note:
When the magnitude of direction changes in circular motion, we say the object is moving in non-uniform circular motion. Here the velocity changes at every point of time, and even though the radius of the circle is constant, the magnitude of radial acceleration is not constant, which means that centripetal acceleration is always at work.