Momentum

• What is the equation for calculating momentum?

  p = mv

  
• What are the units of momentum?

  kilogram metre per second (kg m/s)
• What happens to the momentum of an object at rest?

  An object at rest has no momentum.
• How does momentum affect the direction of an object?

  Momentum keeps an object moving in the same direction.
• Why is it difficult to change the direction of an object with large momentum?

  Because it requires a greater force to change its direction.
• How does the direction of travel affect momentum?

  Momentum depends on the direction of travel since velocity is a vector.
• What does it mean if momentum is positive or negative?

  Positive momentum indicates movement to the right, while negative momentum indicates movement to the left.
• When does the momentum of an object change?

  Momentum changes if the object accelerates, decelerates, changes direction, or its mass changes.
• What is the principle of conservation of momentum?

  The total momentum before an event is equal to the total momentum after the event in a closed system.
• What is a closed system in terms of momentum?

  A closed system is one where energy is constant and there are no external forces acting on it.
• What happens to momentum in a system of objects moving in opposite directions at the same speed?

  The overall momentum of the system will be 0 since they cancel out.
• What is the momentum of mass m moving with velocity u before a collision?

  The momentum is given by \( m \times u \).
• How is momentum calculated after a collision?

  It is calculated as the sum of the momentum of all objects involved.

  
• What is the difference between elastic and inelastic collisions?

  In elastic collisions, objects move in opposite directions, while in inelastic collisions, they move together in the same direction.

  
• What happens to kinetic energy in a perfectly elastic collision?

  Kinetic energy remains the same before and after the collision.

  
• What happens in a perfectly inelastic collision?

  The two objects stick together after colliding.

  
• What is the role of safety features in vehicles regarding momentum?

  They are designed to absorb energy and increase contact time to reduce the force of impact.
• How do crumple zones in vehicles work?

  Crumple zones absorb energy by deforming during a collision, increasing the time taken to come to rest.

  
• What is the purpose of seat belts in a vehicle?

  Seat belts keep passengers fixed to their seats to prevent them from colliding with the interior during a sudden stop.
• How do airbags function during a collision?

  Airbags deploy to act as a cushion, preventing injury when passengers are thrown forward upon impact.

  
• What is the function of crash mats in gymnasiums?

  Crash mats absorb shock and reduce the risk of injury from falls.
• How do playground surfaces help reduce injury risk?

  Cushioned surfaces increase contact time with the ground, reducing the risk of severe injury from falls.
• Why do thinner crash mats work for children but not for adults?

  Children have lower mass and therefore require less cushioning for low-impact activities.
• What is the overall goal of safety features in vehicles and equipment?

  To reduce the chance of serious injury during impacts.
• What is the relationship between force and momentum?

  Force is the rate of change in momentum.

  
• How is the change in momentum defined?

  Change in momentum is defined as final momentum minus initial momentum.
• What is the significance of contact time in reducing impact force?

  Increasing contact time reduces the force experienced during an impact.
• What is the formula for calculating force in relation to momentum?

  Force = change in momentum / change in time.

  
• What is the importance of checking signs in momentum calculations?

  Checking signs helps avoid common calculation errors related to direction.