Effect of Impact Surface on the Coefficient of Restitution and Mechanical Energy Loss of a Bouncing Tennis Ball

When a ball hits the ground, it does not simply stop; it squashes, springs back, and flies upward again. This familiar bounce is a quiet battle between energy and loss. As the ball strikes a surface, some of its motion is preserved, allowing it to rebound, while the rest vanishes into the world as heat, sound, or the permanent bending of materials. Scientists describe this efficiency using a simple idea: how much of the original speed is returned to the object after the crash? If a ball were perfectly elastic, it would return to its exact starting height, losing nothing. In reality, every bounce is a little shorter than the last because the collision is never perfect. The surface the ball hits plays a massive role in this exchange. A hard floor might return most of the energy, while a soft, spongy one might swallow it up. Understanding exactly how different materials handle this collision helps us grasp the basic physics of movement and impact, from sports equipment to the safety features in our cars.

A researcher named Prosper Chanda set out to measure these differences with a standard tennis ball and four very different floors. The experiment was straightforward but precise. A single tennis ball, weighing about 58 grams, was dropped from a fixed height of exactly one meter onto four distinct surfaces: a concrete slab, a ceramic tile, a wooden board, and a rubber mat. For each surface, the ball was dropped ten times, creating a total of forty drops. The researcher did not use high-speed cameras or complex sensors to track speed; instead, the maximum height the ball reached after each bounce was measured directly. By comparing how high the ball started to how high it bounced back, the researcher could calculate how much energy was lost during the impact. This method relies on a simple truth: the higher the ball bounces, the more energy it kept; the lower it bounces, the more energy the surface absorbed.

The results revealed a clear and consistent pattern. The concrete surface was the most forgiving, allowing the ball to rebound to an average height of 0.582 meters. This surface returned the most energy, with the ball losing only about 41.8 percent of its initial power. The ceramic tile was slightly less efficient, with the ball reaching an average height of 0.554 meters and losing 44.6 percent of its energy. The wooden board performed worse still, with the ball bouncing to just 0.497 meters and losing half of its energy, specifically 50.35 percent. The rubber mat was the least efficient of all; the ball barely rose to 0.413 meters, meaning it lost nearly 59 percent of its energy upon impact. The data showed that the harder the surface, the higher the ball bounced, and the softer the surface, the more energy it seemed to drink up.

To ensure these differences were real and not just random luck, the researcher applied a rigorous statistical test to the measurements. The analysis confirmed that the variations in bounce height were not accidental. The difference between the surfaces was so large and consistent that it could not be explained by chance. In fact, the type of surface accounted for nearly all the variation seen in the results. Every single comparison between the surfaces showed a statistically significant difference. The concrete was distinctly different from the tile, the tile from the wood, and the wood from the rubber. There was no overlap in their performance; each material created a unique outcome for the bouncing ball.

The study suggests that the physical nature of the surface dictates how much energy is returned. Harder materials like concrete and tile deform very little when hit, so most of the energy loss comes from the ball itself squashing and reforming. Softer materials like the rubber mat deform significantly under the ball's weight, absorbing a large portion of the impact through their own internal friction and turning that motion into heat. While the experiment did not measure the heat or sound directly, the drop in bounce height serves as a clear indicator of where that energy went. The findings confirm that the surface is not just a passive stage for the ball; it is an active participant that determines how much of the ball's motion survives the collision.

However, the researcher is careful to note that these numbers apply specifically to the conditions of this experiment. Only one tennis ball was used, and only one sample of each surface was tested. A different ball, perhaps with a different internal pressure or age, might behave differently. Similarly, a different piece of wood or a different batch of rubber could yield other results. The study also used only one drop height, and the behavior of a ball can change if it is dropped from much higher or lower. Despite these limitations, the experiment provides a solid, measured look at how everyday surfaces interact with a common object. It shows that even in a simple drop, the material beneath the ball matters deeply, turning a routine bounce into a precise measurement of energy and loss.