Question

A 2 kg metal ball is rolling down a ramp which has 41 degrees with ground

Answer 1

Metal ball on an ramp and you let it start rolling down.

Point Mass vs. Rigid Object —————————

Introductory physics course students work with point masses.  

Sure, they aren't really point masses.  

Baseball isn't a point mass and nor a car.  

But if you are only looking at the motion of the center of mass then it is essentially a point mass.