Circular Motion

Circular motion in physics is exactly how it sounds like: the motion of an object in a circular path(where the object traverses the circumference of a circle). The GIF below shows exactly what circular motion looks like.

This GIF is a perfectly circular, or uniformly circular orbit. If you notice, the point in orbit is rotating at the same rate through the entirety of its path.

Note:There is also something known as an elliptical motion where the object moves around in the namesake manner(an elliptical path).

For an object in a circular motion, we can't simply define its path in terms of velocity because that is always changing due to the object's constantly changing direction. However, if we take the object at a certain instant, it has a tangential velocity vector pointing linearly outside the circle, as seen above in the GIF.

Now, as mentioned before, the speed of the object in circular motion doesn't change, only its velocity(because of its direction) does. This is actually going to be very useful when we try to calculate the circular speed at any time. Remember that speed is simply given as:

However, s(the displacement) won't really be purely linear because otherwise, the object's displacement would be 0 in one revolution. Thus, we need the circular distance that an object covers in one revolution to figure out its circular speed. Luckily, we know what that circular distance is -- it's the circumference of the circular path that the object travels in. The circumference of a circle, as we know, is:

If we just divide this by its orbital period(due to its circular motion), we get the circular speed of the object in its path at all times(because the circular speed is constant). Keep in mind that this speed is still in meters/second.

If we just divide this by its orbital period(due to its circular motion), we get the circular speed of the object in its path at all times(because the circular speed is constant). Keep in mind that this speed is still in meters/second.