8.5 Inelastic Collisions in One Dimension

8.5 Inelastic Collisions in One Dimension

  • Before and after the collision, try to calculate the internal kinetic energy.
    • The internal energy is the same at 4.00 J.
    • You can check the total momentum before and after the collision.
  • Any one-dimensional elastic collision of two objects can be described with the equations written above.
    • If needed, the equations can be extended to more objects.
  • You can vary the number of discs, mass and initial conditions.
    • Take the elasticity and see what happens.
  • In an elastic collision, internal energy is conserved.
    • The forces between colliding objects can remove or add internal energy.
    • The forms of energy within a system may be changed by internal forces.
    • When colliding objects stick together, this internal work may transform some internal energy into heat.
    • When exploding bolts separate a satellite from its launch vehicle, it may be possible to convert stored energy into internal energy.
  • An inelastic collision is when the internal energy changes.
  • An inelastic collision is shown in Figure 8.8.
    • Two objects that have the same mass head toward each other at the same speed.
    • Their total internal energy is initial.
    • After sticking together, the two objects come to rest.
    • The internal energy after the collision is zero.
    • The collision reduces internal energy to the minimum and still conserves energy.
  • The internal energy is not conserved.
    • The internal energy of the system is reduced to zero in this example.
  • The puck goalie system has negligiblefriction between it and the ice.
  • An ice hockey goalie catches a hockey puck.
    • In this inelastic collision, the puck's initial energy is almost completely converted to thermal energy and sound.
  • The puck-goalie system has zero external force.
    • The puck and goalie system can be found using the final velocity of the momentum.
    • The puck and goalie have the same initial and final velocities.
    • Before and after the collision, the kinetic energies can be calculated and compared.
  • The puck-goalie system has zero external force.
  • We know that the goalie is at rest.
    • The final velocities are equal if the goalie catches the puck.
  • The recoil velocity is the same as the puck's original velocity.
  • The goalie is at rest and the internal energy of the system is the hockey puck.
  • The minus sign indicates that the energy was lost.
  • In this perfectly inelastic collision, nearly all of the initial internal energy is lost.
  • Most automobile accidents happen when the objects don't stick together and less of the internal energy is removed.
    • During a collision, stored energy can be converted into internal energy.
  • An air track is very smooth.
    • The motion is only one-dimensional.
  • The sporting and leisure industry uses elastic and inelastic collision in sports.
    • We can briefly look at tennis.
    • In a collision, it is momentum and not force that is important.
    • A heavier tennis racquet has an advantage over a lighter one.
    • A softball bat cannot hit a hardball very far.
  • The location of the tennis ball on the racquet is important, as is the part of the stroke during which the impact occurs.
    • A tennis player tries to hit the ball on the "sweet spot" on the racquet, where the impact is minimized and the ball is able to be given more speed.
    • Sports science and technologies use physics concepts.
  • A tennis, badminton, or other racquet can be found.
  • The elasticity of a collision between a ball and an object is measured by the ratio of the speeds after and before the collision.
    • There is a perfectly elastic collision.
    • A ball bouncing off the floor can be shown to be the height from which the ball is dropped.
    • For the case of a tennis ball bouncing off a concrete or wooden floor, determine for the cases in Part 1 and for the case of a new tennis ball used on a tennis court.