Kinematics

Cards (15)

  • Distance is the total length moved irrespective of direction
  • Displacement is the shortest point from one point to another in a particular direction
  • Speed is the rate of change of distance per unit time
  • Velocity is the rate of change of displacement per unit time
  • Average speed/velocity is the average rate of change of distance/displacement over a unit period of time
  • Instantaneous velocity/speed is the velocity/speed of an object at any particular instant of time
  • Acceleration is the rate of change of velocity per unit time
  • Acceleration of free fall is the acceleration produced when an object falls under the influence of the gravitational force of the earth alone
  • The equation for acceleration due to gravity is g = -9.81 m/s^2
  • Projectile motion is the motion of an object thrown or projected into the air, subjected only to the acceleration of gravity
  • Equations of motion can only be applied for,
    • motion in straight line
    • constant acceleration
  • Determining acceleration of free fall
    • a steel ball is held on an electromagnet
    • when the electromagnet is switched off, the ball interrupts a light beam and a timer starts
    • as the ball falls, it interrupts a second light beam and the timer stops
    • vertical distance h is plotted against t squared
  • Projectile motion is when the uniform velocity acts along the horizontal direction and constant acceleration acts in a perpendicular direction
  • In projectile motion,
    • without air resistance, the horizontal direction is constant, and the vertical direction increases at a constant rate
    • with air resistance, the horizontal direction decreases to 0, and vertical direction increases to a constant value
  • Terminal velocity,
    • for a body in free fall, the only force acting on it is its weight and its acceleration
    • drag force increases as the body accelerates
    • therefore, the acceleration decreases
    • when the drag force is equal to the gravitational pull on the body, the body will no longer accelerate and will fall at a constant velocity
    • this is the maximum velocity that the object can have an is called the terminal velocity