The so-called Kinetic energy is simply said to mean that objects have energy due to motion. number is tantamount to (1/2) Mv^2. Kinetic energy is one kind of energy, its unit under the International system of units is joule (J), short for joule. It should be noted that Kinetic energy (and the work corresponding to it) both are Scalar quantity, that is, there is only magnitude and no direction. When summing, it only calculates the number sum, which does not satisfy the vector (called vector in math) in addition to parallelogram rule.

Kinetic energy theorem

formulas ： E_k = ½ mv²

Quality ： m = E_k / ½ v²

speed ：v²=2E_k / m