Titleist Golf Balls at The Moment of Impact

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Recommends Cort Ammon · 2019-02 · Physics Stack Exchange · on “Why do objects rebound after hitting the ground?”

A video's worth a thousand words. Here's one of a tennis ball [LINK] showing exactly what Farcher is talking about. Elastic potentials build up as the ball stretches. You may not think of the material in a shoe doing this, but you'd be surprised how much solid looking objects deform [this video] when you see them in slow motion. Not so solid objects [LINK] are pretty funny too.

Recommends Thomas Fritsch · 2020-11 · Physics Stack Exchange · on “Infinite force during head to head elastic collisions”

The time of collision is zero here therefore force must be infinite . Is this correct ? Something doesn't feel right here. Can Infinite force act ? You have been tricked by an idealization, and took it for reality. In order to make explanations simpler the colliding bodies are often treated as being infinitely hard. An infinitely hard body would not deform. And therefore the collision would happen in zero time ( $\Delta t=0$ ), and hence the force would be infinitely high ( $F= \infty$ ) during this time. But nevertheless, this is not reality, but only a simplifying idealization. In reality the colliding bodies may be very hard, but not infinitely hard. Even billard balls will deform a littl

Recommends mmesser314 · 2023-06 · Physics Stack Exchange · on “Velocity at impact”

Typically a ball is idealized as a point particle or rigid object. A collision is idealized as instantaneous. The idealizations work for problems where you ask about velocity before and after. But they fail when you ask about what goes on during a collision. Forces are reasonably small before a collision, typically $1$ g. A ball can stay reasonably rigid under forces like this. A collision changes the velocity to $0$ in a very short time (usually). Accelerations and forces are very large. It isn't simple to analyze. Different parts of the ball can move at different speeds. If you do analyze it, every part decelerates to $0$ in a continuous way. If the collision is elastic, every part acceler

Recommends mmesser314 · 2026-02 · Physics Stack Exchange · on “Understanding the behaviour of a cue ball in billiards after it strikes another ball”

Physics problems often look at the before and after of a collision as exercises of conservation laws. The momentum before is the same as the momentum after. They ignore what happens during the collision. Collisions are abrupt changes in velocity. Forces before and after are $0$ . During the collision, they are very large for a very brief time. You often cannot treat the balls as rigid objects. They must be treated as collections of parts that move differently from each other. Here is a video from Titleist showing how their golf balls behave when struck by a club. Titleist Golf Balls at The Moment of Impact [this video] This is more complex than you want for the usual problem. But it is possible t

Cites mmesser314 · 2021-03 · Physics Stack Exchange · on “Forces in an elastic 1D collision”

The way you have set up this question makes it a little unclear. You have two blocks with different masses and accelerations. You can calculate the forces, and they are different. Perhaps you have two different blocks with two different ropes on them. You pull on the ropes and the objects accelerate. Forces always occur in equal and opposite pairs. If you pull on a rope to accelerate an object toward yourself, the rope also pulls on you toward the object. See Why is the tension on both sides of an Atwood machine identical? [LINK] The situation is different when the objects collide. They exert equal and opposite forces on each other. Often people don't ask about the forces during a collision.

Cites Cort Ammon · 2021-04 · Physics Stack Exchange · on “Why do object rotate at all?”

I can't skip the mathematics bit of the puzzle. Rotation and angular momentum are fundamental properties of a "rigid body." This is the superficial answer, but its an important piece of the puzzle. It lets us reframe your question as to why a rigid body is such a good model of real life objects and their behaviors. This is fun because its so easy to show that it isn't always a good model. Some really demonstrate [this video] how not-instantanious things are. Others are just fun in a certain schadenfreude [LINK] way. When we get down to brass tacks (or any material), we find that objects aren't actually rigid. When you push somewhere on the surface of an object, that force is spread through the ob

Cites mmesser314 · 2022-09 · Physics Stack Exchange · on “Explaining which hurts more”

This situation is a little harder to understand than we would like because it involves a collision. Most collisions happen very quickly. Usually we don't analyze what goes on during the collision. We just look at the velocities before and after. We ask questions about conservation of momentum and energy. But here you are asked what goes on during the collision. You put a brick next to you and hit it with a hammer. It doesn't hurt as much as if you substitute a piece of paper. But it isn't obvious what goes on during the collision. It is over so quickly you can't see it. So lets look at a collision. Suppose you have an electron at rest. Suppose another electron approaches it slowly enough tha

Cites mmesser314 · 2024-07 · Physics Stack Exchange · on “Extra force in other frame paradox”

In such collision problems, you usually do not look at the forces during the collision. You look at velocities, momenta, and or energies before and after. These are usually problems about conservation laws. Think of a soft, springy rubber ball bouncing off the floor. It flattens as it hits the floor. Parts of it stretch. Kinetic energy turns into potential energy. The forces needed to stretch the ball slow it to a stop. The stretched parts spring back. The forces throw the ball off the floor, converting potential energy into kinetic energy. Harder balls like steel and wood are harder to deform. They may deform very little. If so, the collision takes place in the very short time they are in c

Cites mmesser314 · 2025-05 · Physics Stack Exchange · on “Throwing vs Hitting a Ball”

Throwing and hitting a ball are really the same thing. In both cases, a hand or club applies a force to the ball, accelerating it. Then the ball leaves and follows a trajectory. The forces are gravity and drag from air. If drag is small enough to ignore, the trajectory is parabolic. The difference between throwing and hitting is the size of the forces and how long the interaction lasts. Collisions can produce enormous force for a very short time. This is from Titleist Golf Balls at The Moment of Impact [this video] [LINK] Often the forces during collisions are difficult to analyze. They may not the same everywhere in an object. In the picture, the forces on the left side of the golf ball have def