Science G8 Q1

• When a car exhilarates abruptly


  Your body is pulled to the back
• When the driver suddenly steps on the brakes

  You feel the seat belt tighten
• Newton's first law of motion

  The law of inertia, it explains how an object responds to changes in motion
• Force


  Any push or pull that causes changes in the motion of an object
• Types of force


  • Contact force
  • Non-contact force
• Contact force


  Present when two or more surfaces or media touch and interact
• Friction


  A specific type of contact force, the object's resistance to motion
• Non-contact force


  Constantly present in nature and does not need human intervention to arise
• Motion


  Caused by unbalanced forces and can be described with speed, velocity and acceleration
• Speed


  The length of distance traveled in a certain amount of time
• Velocity


  The rate of change of displacement of an object
• Acceleration


  The rate of change of velocity of an object
• Newton's first law of motion

  An object at rest will remain at rest unless acted on by an unbalanced force, and an object in motion continues to move with the same velocity unless acted on by an imbalanced force
• Inertia


  The property that resists the changes in an object, it is independent from external force and mass dependent
• Coin, glass and cardboard experiment

  1. Slowly pull the cardboard

  2. Quickly flick the cardboard
• An object at rest will remain at rest and an object in motion will remain in motion unless acted on by an unbalanced force</b>
• Newton's second law of motion

  The acceleration of an object is directly proportional to the net force on it and inversely proportional to its mass
• Newton's law of acceleration

  Force acting on an object = Mass of object x Acceleration of object
• Greater mass of object


  Greater force needed to accelerate it
• Force = Mass x Acceleration
• Acceleration = Sum of forces / Mass
• Mass = Sum of forces / Acceleration
• Unit of force


  Newton (1 N = 1 kg m/s^2)
• Weight


  Force due to gravity = Mass x Acceleration due to gravity (9.8 m/s^2)
• Calculating force for rocket acceleration

  Force = Mass x Acceleration (45,000 kg x 70 m/s^2 = 3,150,000 N)
• Calculating acceleration of 0.6 kg ball with 12 N force

  Acceleration = Force / Mass (12 N / 0.6 kg = 20 m/s^2)
• Calculating mass of encyclopedia with 15 N force and 5 m/s^2 acceleration

  Mass = Force / Acceleration (15 N / 5 m/s^2 = 3 kg)