You know a simple model of a physical body – a material point and a more complex one – a mathematical pendulum. Show by the example of these models that a more complex model does not deny a simpler one, but, on the contrary, retains its most important features.
In a mathematical pendulum, the load can be taken as a material point, since its dimensions are much less than the length of the thread on which it is held. By studying the oscillations of the pendulum, Huygens invented the first pendulum clock.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.