STUDY ON NON HIGH SPEED VERTICAL UPWARD THROWING MOTION OF ORDINARY SMALL BALL IN AIR

Firstly, it is proved that it is completely feasible to take the air resistance coefficient C_D as 0.42 for the vertical upward throwing motion of a small solid ball with usual material, size and initial velocity (non high speed) in the air. The air resistance is regarded as the quadratic function of speed in this paper, and the traditional research idea is adopted to gradually deduce the kinematic equation of the non high speed vertical throwing motion of an ordinary small ball in the air, and then deduce the rising time and maximum height of the small ball, as well as the falling time and landing speed. The results show that the rising time of the small ball is less than the falling time, while the latter is less than the rising or falling time without air resistance. At the same initial velocity, the motion of a homogeneous solid bigger ball is less affected by air resistance. When the initial velocity is the same and the product of density and radius is the same, the solid balls with different materials and sizes have the same upward throwing motion. Taking a small solid iron ball with a radius of 1 cm as an example, the variation curves of various motion characteristic parameters with initial velocity and the variation curves of small ball displacement with time under several different initial velocities are calculated and made. The results show that the larger the initial velocity is, the more the motion of the ball deviates from the ideal situation without air resistance. At the end of the paper, some possible interference or error factors are briefly summarized.