In a rail yard, a rolling freight car meets a parked one. The coupler clicks shut. From that click on, the two cars roll down the track as one object, at one velocity.
When a collision transforms some of the system's kinetic energy into other forms such as heat, sound, or deformation, we call it inelastic. Some inelastic collisions go one step further: the objects do not just lose kinetic energy. They stay together.
Watch the freight cars again. Before the impact, two objects move separately. After the impact, the coupler holds them, and they move as one object.
When colliding objects stick together and move as one afterward, we call the collision perfectly inelastic.
Now take the same two cars with the coupler removed. They collide, the impact rings out, and they roll apart separately. Some kinetic energy became sound, so the collision is inelastic. But the cars separate, so it is not perfectly inelastic.
The sorting line sits there: a perfectly inelastic collision is an inelastic collision in which the objects also stick together. If the objects separate after the impact, the collision is not perfectly inelastic, however much kinetic energy it transforms.
The sticking takes many forms. An arrow lodges in a hay-bale target on a cart, and the bale slides back with the arrow in it. One object afterward: perfectly inelastic.
A moving ice skater grabs a resting skater, and the pair glides off together. One object afterward: perfectly inelastic.
The test is one question: after the impact, do the objects move as one? Yes means perfectly inelastic.
A dart with a sticky tip hits a foam block on wheels, lodges in it, and the block rolls back with the dart in it. Which kind of collision is this?
Two bumper cars hit, their rubber rims lock together, and they slide on as a pair. Is the collision perfectly inelastic?
After the impact, the two cars move as one object.
Colliding objects that stick together and move as one afterward make a perfectly inelastic collision.
Yes. The cars move as one afterward, so the collision is perfectly inelastic.
Two bumper cars hit and bounce apart, and the impact dents one rim. Is the collision perfectly inelastic?
The dent shows that some kinetic energy was transformed, so the collision is inelastic.
But the cars separate after the impact, so they do not move as one.
No. The cars separate afterward, so the collision is inelastic but not perfectly inelastic.
Nico says: 'A moving skater grabs a resting skater and the two glide off together. Because they move as one afterward, the collision is perfectly inelastic.' Is he correct?
Which observation alone shows that a collision is perfectly inelastic?
In which case is the collision perfectly inelastic?
Which statement about perfectly inelastic collisions is correct?
A shopping cart bumps the cart ahead, their frames latch, and the pair rolls on as one object. Type the name for this kind of collision.