Can someone please explain the process of a ball bouncing in terms of Forces?
First, it doesn't make sense to say that the normal force is greater than that of the upwards force. When the ball hits the ground and gradually starts exerting the force of its weight, the ground exerts the same equal force just in the opposite direction. The ball starts compressing and ultimately, when it reaches $0 \ \ m/s$, it stops.
Now, the common explanation here is that, due to this compression, the ball pushes back creating a bigger upwards force and hence an upwards acceleration but I think this explanation is simply false or not adequate enough. The ball, due to its compression, pushes the floor. Meaning the force downwards now is $F_g+F_e$ (Weight and the elastic force), from this then follows that the upwards force is exactly the same $F_g+F_e$ just in different directions. This implies that since there is no net force in the upwards direction, there should be no acceleration in the upward direction and thereby the velocity of the ball will stay at $0 \ \ m/s$.
Is it even possible to explain this without mentioning energy and momentum?
Best Answer
I agree. The normal force is the upward force. If the normal force is greater than the weight of the ball, it will be accelerating upward.
Sort of. Just be sure you understand what the forces are acting on. The downward force from the ball is acting on the ground. The upward force from the ground is acting on the ball. Also it is probably simpler to describe the contact/elastic force as a single force not added to gravity, $F_e$. It just so happens that at maximum compression, $|F_e| > |F_g|$. When the ball is just sitting on floor the two magnitudes are equal.
No. We consider only the forces acting on a single object to determine its acceleration. The only forces on the ball are the upward/normal force from the floor (which I describe as $F_e$) and gravity ($-F_g$). This means there is a net force on the ball because the two forces are not equal.