Science/ 1st SA

• Kinetic energy


  Energy associated with an object in motion
• Changing velocity, accelerating (or decelerating)

  1. Force is being applied

  2. Object's mass stays constant

  3. Momentum is changing
• Person stopping


  • More mass
  • More momentum
  • Less stopping distance
• Perfectly inelastic collision


  Two objects collide and move together as one mass after collision
• Two objects moving at same speed


  The one with greater mass has more momentum
• Law of inertia (Newton's first law of motion)


  An object will remain at rest or in uniform motion in a straight line unless acted upon by an external force
• Law of inertia


  • Teetering on edge of cliff or tall building with heavy physics book
  • Body and book have inertia and resist changes in state of motion
• During a collision, the overall or total velocity of the colliding objects is conserved
• Impulse


  A vector quantity
• Momentum


  • Varies directly with speed of object
  • Object moving at constant speed has momentum
  • A vector quantity
• There is a change in velocity when the object moves around a curve, changing paths, and moving then suddenly stops
• You can ignore air resistance when an object falling toward the surface of the earth has a velocity that is constant
• Two objects running at different velocities will hit the ground at the same distance (assuming no air resistance), as the horizontal component of their velocities remains constant
• Inelastic collision


  Internal kinetic energy is conserved
• In an inelastic collision, the kinetic energy of the system is not conserved, but momentum is conserved
• Law of Conservation of Energy


  Energy cannot be created or destroyed, it can only be transformed
• A moving object will eventually come to a stop due to friction because all of the energy in the system was transformed into thermal energy
• Elastic collision


  Two bowling balls collide head on and bounce off one another
• A projectile's velocity changes because of gravity, and its velocity remains constant
• If KE is increasing


  PE will decrease, and vice versa
• Gravitational potential energy


  Directly proportional to an object's mass, the acceleration due to gravity, and the height above a reference point
• The principle of conservation of energy states that the total energy in a system is constant, the total energy gained by the system is equal to the total energy lost, and the total initial energy in a system is equal to its total final energy