The Bounce of a Ball Lab Report

Part 1: Introduction * Background ＆ Theory
In an inelastic collision, total mechanical energy will decrease after the collision, so the magnitudes of the velocities will also decrease during the process. The Coefficient Of Restitution (COP) measures the elasticity of a pair of objects in collision and is the ratio of their final relative speed to their initial relative speed. It depends on the material it is made of, the material characteristics of the objects it collided with, and the initial speeds of all objects involved in the collision.

The coefficients of restitution can be calculated as follows. CR=vu=hH , where v is the rebound speed, u is the speed just before impact, h is the bounce height, H is the drop height. (assume air resistance is negligible)

This is because energy is conserved, so E(K)=12mv2.
The formula of the potential energy: E(P)=mgh (g=9.8N/kg).

* Aim
The aim of this experiment is to investigate COR of different balls when dropped from various heights, and find out the changes of the kinetic energy and potential energy

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Part 2: Methodology * Apparatus 1. Motion Sensor 2. Passport USB Link 3. PASCO Force Platform PS-2141 4. Desktop computer and Datastudio program 5. Basketball, Soccer ball

* Procedures 1. Setup the apparatus as shown in Figure 1 .

Figure 1 2. Ensure that both the motion sensor and force platform are connected to the USB Link properly. 3. Start DataStudio on the desktop computer. Set the sampling rate of the motion sensor to 50 Hz. Set the sampling rate of the force platform to 1000 Hz. 4. Calibrate the exact distance of the motion sensor (Under ”Motion sensor” tab).Check all Position, Velocity and Acceleration (Under ”Measurement” tab). 5. Raise the basketball and hold it under the motion sensor, and let go. Try to release toward the center of