Rev#1_Physics

• Zero acceleration, constant velocity

  • x = displacement
  • v = velocity
  • a = acceleration
  • t = time
• Constant acceleration, increasing velocity

  • x = displacement
  • v = velocity
  • a = acceleration
  • t = time
• Ideal linear motion


  1. Uniform Motion - motion with constant velocity

  2. Uniform Accelerated Motion - motion with constant acceleration

  3. Freefall - motion under influence of gravity

  4. Projectile Motion - curved motion acted upon by gravity
• Uniform Motion


  • Ax = vt
  • Ax = x - xo
  • v = velocity
  • t = time
• Uniform Motion


  • Displacement of a car moving at constant velocity of 20m/s after 2 seconds
• Uniform Accelerated Motion


  • V₁=V.+ + at
  • x=X¸+V¸t+ at/2
  • V²₁ =V²+2aAX
  • V final velocity
  • V. initial velocity
  • a = acceleration
  • t = time
  • X = final position
  • X initial position
  • AX X Xo, displacement
• Uniform Accelerated Motion


  • Acceleration of a cyclist moving from 2m/s to 4m/s in 2 seconds
• Freefall


  • V₁ =V₁+gt
  • y=y+Vt+ gt²/2
  • V²=V²+2gAY
  • AY=(V+V)t/2
  • g=-9.8m/s², gravitational acceleration
  • V final velocity
  • V. initial velocity
  • t = time
  • y = final position
  • y initial position
  • AY y y, displacement
• Freefall


  • Velocity of a ball dropped from a building after 5 seconds
  • Displacement of a mango falling from a tree after 0.5 seconds
• Projectile Motion


  • Neglect air resistance
  • Horizontal and vertical motions are independent
  • Horizontal motion is uniform
  • Vertical motion is freefall
  • Velocity sign is positive for upward, negative for downward
  • Velocity is zero at maximum height
  • Time to reach maximum height = time to fall back to same height
• Newton's Laws of Motion
• First Law of Motion (Law of Inertia)

  Every material continues to be at rest if it is at rest or in uniform motion if it is in motion, unless it is compelled to change that state by forces acted upon it
• Second Law of Motion (Law of acceleration)

  The acceleration of an object is directly proportional to the net force acting on the object, is in the direction of the net force, and is inversely proportional to the mass of the object
• Third Law of Motion (Law of action-reaction)


  Whenever one object exerts a force on a second object, the second object, exerts an equal and opposite force
• Momentum


  Momentum is a physical quantity obtained when the mass of an object is multiplied to its velocity
• Momentum


  • Momentum of a 40,000kg truck travelling at 50m/s
• Impulse


  Impulse is a vector quantity that has the same direction as the force. It is equal to the product of force and time. It is also associated with the change of momentum.
• Vector


  A quantity which is expressed by magnitude and direction
• Scalar


  A quantity which is expressed by magnitude only
• Finding the resultant vector

  Add or subtract the vectors
• A mango falls from a tree


  • How far does it fall after 0.5 seconds?
• Finding ΔY


  1. t = 0.5 s

  2. Vo= 0

  3. ΔY=Vot+1/2gt²

  4. ΔY=0(0.5)+1/2(-9.8)(0.5)²

  5. ΔY = -19.6 m
• Projectile Motion


  Curved motion of an object that is projected into the air and acted upon by the force of gravity
• Scalar quantity


  A quantity which is expressed by magnitude only
• Scalar quantities


  • Mass
  • Time
  • Temperature
  • Area
  • Distance
• Vector quantity


  A quantity which is expressed by magnitude and direction
• Vector quantities


  • Force
  • Velocity
  • Weight
  • Acceleration
  • Displacement
• Arrow representing a vector

  • Arrowhead indicates direction
  • Length represents magnitude
  • Tail represents origin
• Resultant vector


  Sum/difference of two or more vectors which will give the same effect as the original vectors
• Finding resultant vector


  1. Addition if vectors have same direction

  2. Subtraction if vectors are acting in opposite directions

  3. Pythagorean Theorem if vectors are at right angles

  4. Component method if vectors are acting in different directions
• Momentum is the product of mass and velocity
• Impulse


  Vector quantity equal to the product of force and time, associated with change in momentum
• Law of Conservation of Momentum

  Total momentum of a system remains constant if net external forces are zero
• Instantaneous Speed


  Speed at a particular instant in time
• Velocity


  Rate of motion with direction
• Acceleration


  Rate of change of velocity
• Graphs can relate displacement, velocity and acceleration
• Linear Motion


  Change in position of an object relative to other objects considered at rest
• Distance


  Total path length traveled by a body
• Displacement


  Change in position of an object, straight line path between start and end