A pendulum is held vertically and is then released, impacting a cart that is initially at rest. This experiment provides students with a lesson for comparing theory with actual experimental results and explaining any differences. A variety of physics principles, including conservation of energy, conservation of momentum, and impulse, are incorporated into the experiment. VelocityLab is used to determine the actual speed of the cart after the impact, and the students compare this to speed predictions based upon theory. In addition, students use impulse concepts to calculate the force during impact.