Momentum

• Momentum can be thought of as a combination of mass and velocity
• Momentum helps explain important interactions in nature
• Momentum is calculated by multiplying an object's mass by its velocity
• Momentum is a vector quantity, meaning it has both magnitude and direction
• An object has no momentum when it is standing still, but gains momentum in the direction it is moving
• Momentum can be calculated using the equation: momentum = mass × velocity (p = m * v)
• Momentum is measured in kilogram metres per second (kg m/s)
• Mass is measured in kilograms (kg)
• Velocity is measured in metres per second (m/s)
• Conservation of momentum principle: total momentum before an event equals total momentum after the event in a closed system
• Closed system: not affected by external forces
• Momentum is conserved in collisions and explosions
• Conservation of momentum explains why a gun or cannon recoils backwards when fired
• Calculations involving collisions:

  • Use the principle of conservation of momentum to calculate the velocity of combined objects after collision
• Key fact:

  • Momentum is a vector quantity, considering both magnitude and direction
• Momentum can be thought of as a combination of mass and velocity
• Momentum helps explain important interactions in nature
• When a force acts on a moving object, there is a change in momentum
• Change in momentum is calculated by multiplying mass by velocity
• Force involved in a change in momentum is equal to the rate of change of momentum
• Force = mass × acceleration
• Acceleration = change in velocity / time taken
• Force = change in momentum / time taken
• Force is measured in newtons (N), change in momentum in kg m/s, and time taken in seconds (s)
• Car safety features like seatbelts, airbags, and crumple zones work to decrease the force of collision by increasing the time taken for the collision
• Crumple zones deform on impact to decrease the force of collision
• Safety features decrease the rate of change of momentum, reducing the force of collision on people in the car