PHYSICS

• 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
  • Acceleration
  • Displacement
  • Weight
• Arrow


  • Used to represent a vector
  • Arrowhead indicates the direction of the vector
  • Length of the arrow represents the magnitude of the vector
  • Tail represents the origin of the vector
• Resultant vector


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

  1. Addition - if vectors have the same direction

  2. Subtraction - if vectors are acting on opposite directions, the resultant vector takes the direction of the larger vector

  3. Pythagorean Theorem - if vectors are acting at a right angle with one another
• Addition of vectors

  • Kelly walks 2 meters to the east, then 3 meters to the same direction. Displacement = 5m to the east
• Subtraction of vectors

  • Ball tossed upward 5m, then moved downwards 10m. Displacement = -5m
• Pythagorean Theorem

  • Marivic walks 2km north, then 1.5km east. Displacement = 2.5km
• Component Method – if several vectors are acting on different directions, x and y component are mathematically added to find the resultant vector.
• Example: An airplane flies in a northeasterly direction at 100kph at the same time that there is a wind blowing at 20kph to the northwest. What is the resultant velocity of the plane?

  84.85kph

  A)

  
•  Freefall - a good example of uniform accelerated motion

    - one dimensional motion where the moving object is only under the influence of gravity

    - gravitational acceleration is equal to -9.8m/s2
• Uniform Accelerated Motion – motion with constant acceleration
• Uniform Motion – motion with constant velocity
• • Acceleration – rate of change of velocity
• • Velocity – rate of motion with direction
• Speed – measure of how fast an object travels
• Motion – change in position of an object relative to other objects that are considered at rest.
• Distance – total path length traveled by a body.
• Displacement – change in position of an object. It represents the straight line path between the starting and end points.
• Projectile Motion – curved motion of an object that is projected into the air and acted upon by the gravitational force of the earth

        - a combination of uniform motion and freefall
• 1. Newton’s Laws of Motion

  • explains why objects move, and define the relationship between the external forces acting on a body – as well as between two or more interacting bodies and the motion that arises from the action of these forces.
• 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.”
• Inertia – is the tendency of an object to resist a change in its state of motion

  Mass – is a measure of an object’s inertia

  Weight – force acted upon an object due to gravity

  Force – a push or a pull (e.g. gravitational force, friction, normal forces, electromagnetic force, etc.)
• 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

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

  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.
• capacity to do work

        - a scalar quantity

  energy
• The energy stored on an object due to its position.

  Potential Energy
•  energy stored on an elastic material due to its stretching or compressing

  Elastic Potential
• energy of an object in motion

  Kinetic Energy
•  the product of force and displacement

  work
•  any string interaction between two bodies that lasts a relatively short time

  collision
• after the collision, the objects is still separatd from each other

  elastic collision
• after the collision, the objects move as one unit

  inelastic collision
• Range – horizontal distance covered by a projectile
• Time of flight – time in which the projectile is up in the air
• Trajectory – curve traced by the path of the projectile