The purpose of this study is to find out the optimum launch angle for maximizing the long jump from a kinematic point of view. The optimum launch angle of a long jump in the horizontal plane is calculated using the simple mathematical model by the law of conservation of energy when the air resistance is neglected and considered for each. To have the solutions of the range equation (8) and (15), Newton-Raphson method for differentiating the equation with respect to launch angle ais used. For various initial speed v0 the optimum launch angle a_m is obtained as about 32 - 33 degree for maximum range 6.78 - 9.35 m. According to model calculation, at the limiting speed 11.5 m/s by Carl Lewis the result of this study shows that with such a running speed, it is theoretically possible to long jump 9.35 m, this distance may be considered as the upper limit of long jumping at the present time. Also this model suggests that new world record of 9m will be achieved in long jump.