Momentum

• What do all moving objects have?

  Momentum
• What is the equation to calculate momentum?

  Momentum equals mass multiplied by velocity
• What is the unit of momentum?

  Kilogram m/s
• A car has a mass of 1,000 kg and is not moving; what is the momentum of the car?

  Zero
• A car has a mass of 1,000 kg and is moving at 20 m/s; what is the momentum of the car?

  20,000 kg m/s
• What principle is being described when it is stated that in a closed system the total momentum before an event equals the total momentum after an event?

  Conservation of momentum
• In a closed system, what is the relationship between total momentum before and after an event?


  They are equal
• What is the total momentum before firing when a cannon contains a cannonball and neither is moving?

  0
• After a cannon fires a cannonball in the forward direction, in which direction does the cannon recoil?

  Backwards
• After the cannon fires, what is the relationship between the backward momentum of the cannon and the forward momentum of the cannonball?

  They are equal
• How do you calculate momentum using mass and velocity?

  • Momentum = mass * velocity
• What is the formula for calculating momentum?

  Momentum equals mass multiplied by velocity
• In a closed system, what is the relationship between the total momentum before and after an event?

  Total momentum before equals total momentum after
• A van with a mass of 2,000 kg is traveling at 30 m/s and collides with a stationary car with a mass of 800 kg; what is the van's momentum before the collision?

  60,000 kg m/s
• A van with a mass of 1,400 kg is traveling at 20 m/s; what is the momentum of the van?

  28,000 kg m/s
• A van with a momentum of 28,000 kg m/s collides with a stationary car of mass 1,000 kg, what is the total mass after collision?

  2,400 kg
• If the total momentum is 28,000 kg m/s and the combined mass of the van and car is 2,400 kg, what is the velocity of the van and car together after the collision?

  11.67 m/s
• What two quantities are multiplied to calculate momentum?

  Mass and velocity
• Why are rapid changes in momentum dangerous?

  They can lead to extremely dangerous forces.
• What do car manufacturers use to design safety features?

  Crash tests
• During a car crash, what happens to the momentum of the passengers?

  It falls from a large amount to zero.
• What does the rapid decrease in momentum during a car crash cause?

  Huge forces on the passengers
• What equation can calculate the force acting on an object?

  Force = mass × acceleration
• How is acceleration calculated?

  Change in velocity / time taken
• What is the formula to calculate force using mass, change in velocity, and change in time?

  Force = (mass × change in velocity) / change in time
• In the equation force = (mass × change in velocity) / change in time, which part is the change in momentum?

  Mass multiplied by the change in velocity
• What is the force acting on an object equal to?

  Change in momentum / time
• A man with a mass of 100 kg is in a car traveling at 30 m/s, and the car stops in 1 second. What is the force acting on the man?

  3000 Newtons
• How can the danger from rapid changes in momentum be reduced?

  By making the change happen over a longer time
• What are some safety devices that slow down momentum change?

  • Airbags in a car
  • Seatbelts in a car
  • Crash mat in athletics
  • Bike helmet
  • Cushioned surface in a playground
• How do safety devices reduce the risk of serious injury?

  By slowing down momentum change