Collisions

• What is always conserved in collisions and explosions?

  Momentum
• What might not always be conserved in collisions?

  Kinetic energy

  
• How is a collision classified as elastic or inelastic?

  • Elastic: Kinetic energy is conserved
  • Inelastic: Kinetic energy is not conserved

  
• What happens in elastic collisions?

  Objects do not stick and move apart
• What happens in inelastic collisions?

  Objects stick together after collision

  
• What is commonly associated with explosions?

  Recoil
• How can you determine if a collision is elastic or inelastic?

  Compare kinetic energy before and after

  
• What is the equation for kinetic energy?

  Kinetic energy = 0.5 * mass * velocity^2

  
• What type of collision occurs when two trolleys stick together?

  Inelastic collision
• How does increasing contact time affect force during a collision?

  It reduces the force exerted
• What are the safety features in vehicles designed to do during a collision?

  • Absorb energy from the impact
  • Increase contact time to reduce force
  • Minimize risk of injury to passengers
• What is the purpose of seat belts in vehicles?

  To keep passengers fixed to their seat
• How do seat belts reduce force during a collision?

  By stretching to increase contact time

  
• What do airbags do during a collision?

  Act as a cushion to prevent injury
• How do airbags help reduce force on passengers?

  By increasing contact time during impact

  
• What are crumple zones designed to do?

  Crush in a controlled way during collisions
• Why do vehicles appear heavily damaged after small collisions?

  Crumple zones absorb impact energy
• How does increased contact time affect force on a force-time graph?

  It results in a lower peak and wider base

  
• What does the increase in contact time Δt do to force for the same impulse?

  It decreases the force