2

• location


  b-->a

  a's location to b,
• displacement


  scalar, related to velocity, distance between initial and final locations no matter how long it took or how much to reach there
• speed & velocity


  av speed= distance moved/ time taken

  velocity= has direction
• acceleration


  av acceleration= change in velocity/ time taken
• a negative acceleration is called deceleration or retardation.
• during acceleration, acceleration and velocity vectors are same ways.


  during deceleration, deceleration and velocity vectors are opposite ways
• distance-time graphs

  gradient= speed
• speed-time graphs


  gradient= numerically equal to acceleration

  area under the line= numerically equal to the distance travelled
• Free fall


  Falling under the influence of gravity alone, without air resistance
• g (acceleration of free fall)

  9.8 m/s^2
• Parachute jumping

  1. First seconds, the parachutist is falling faster (accelerating)

  2. As velocity increases, the air resistance will increase, (up-forces= weight) which leads to reaching a constant velocity called "terminal velocity"

  3. When he opens the parachute, the air resistance increases so he slows down gradually (decelerating)

  4. But decreasing velocity leads to decrease the air resistance

  5. When he slows down the forces become balanced again, leads to constant velocity again "terminal velocity"

  6. When he touches the ground his velocity reach zero in no time
• free fall last point


  His weight downward equals the push of ground to him upwards

• resultant forc

  f= m. a
• drag


  friction in liquid or gas
• friction static/ dynamic


  s: while stedy, no movement

  d: while moving

  s> d (need of force or friction rate)
• understand it gal:3


  open the notebook

  
• weight


  W= m. g

  (g= 10N/kg)
• newton's third law of motion

  to every action there is an equal but opposite reation