Physics Paper 1- MOMENTUM AND NEWTONS LAWS

• Newton's first law

  An object will remain in a state of rest or a constant velocity unless it's acted upon by an external force
• Newton's second law

  The net force on an object is proportional to the rate of change of momentum and it's also in the same direction
• Newton's third law

  When two objects interact they exert equal and opposite forces on each other
• Shower head example of Newton's second law

  1. Find the force from the water on the shower head

  2. Use F = rate of change of momentum

  3. Substitute values for density, area, and velocity
• Impulse

  The average net force acting on an object multiplied by the time it acts on it
• Impulse is equal to the change in momentum
• Impulse can be found as the area under a force-time graph
• Momentum

  The mass of an object times its velocity
• Collision problem - finding common velocity

  1. Use conservation of momentum

  2. Set up equation with initial and final momenta

  3. Solve for final common velocity of 3.3 m/s
• Perfectly elastic collision

  Kinetic energy and momentum are conserved, objects tend to move away from each other
• Perfectly inelastic collision

  Momentum is conserved, objects tend to stick together and move at a common velocity