Why do i need to use the unit circle in physics? and how do i use it?

The unit circle helps in making so many calculations and equations easy.

Explanation:

You cannot separate the knowledge of trigonometry to application in equations to physics. The unit circle is known to have a radius of one. This means that the distance from the centre of the circle, regardless of the unit of measurement, to any point of the edge of the circle is 1. Since the unit circle is very helpful in trigonometry, and trigonometry in turn is the projection of triangles and angles that is very crucial in the calculation of momentum, velocity and other factors of physics, the importance of the unit circle cannot be overemphasized in physics.

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.

elctricity and magnet is conversion to it