# Ballistic Pendulum Lab

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Lab 8: Ballistic Pendulum Objective: In this lab we used three methods to measure the initial velocity of a projectile from a spring gun. In the first experiment we used kinematics alone to determine the mean initial velocity for the projectile. In the second experiment we added a simple ballistic pendulum to derive the velocity of the projectile using the principles of conservation of momentum and energy. In the third experiment we used a physical pendulum, the equations for conservation of angular momentum and energy, and the equation for the period to determine the initial velocity of the projectile. Description: In these series of experiments the apparatus we used was a spring gun that for the first experiment shot a steel ball freely which eventually struck the floor. For the second and third experiments the gun fired the steel ball into a pendulum. To measure the velocity of the steel ball, when it was launched freely, carbon paper and a 2-meter ruler were used to determine the distance it travelled and then kinematics were used to calculate the balls initial velocity. When the steel ball was launched into the pendulum the laws of conservation of energy and momentum were utilized to determine the balls initial velocity. Theory: 3 Kinematic Measurement of Speed In this experiment the steel ball was moving in two dimensions both horizontally and vertically. Since these two components of motion are independent of one another, two sets of equations are used- one for the balls horizontal motion and one for its vertical motion. For the horizontal component, there are no external forces acting on the ball. Therefore there is no acceleration and the ball moves at a constant velocity. The distance the ball travels in the horizontal direction can be calculated using . For the vertical component, the only force acting on the ball is gravity making