For the Newton's pendulum, a new model is established using the Hertzian contact theory to represent the interactions between adjacent balls. This model is applied to solve the problems of a ball chain collision, with the impulse wave propagation in the chain. By changing the number of the balls, the influence of the ball-chain length is studied. Numerical calculations provide information of the position, the velocity of each ball, and the deformations and the interaction forces between the adjacent balls, as functions of time. A computer tool with graphic user interface (GUI) is developed to solve the ball-chain impact problems in different situations. The high speed camera is used in the collision experiments to study the detailed process, showing that the numerical model gives good predictions.