Transport: Forces at Work

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  1. forces can change what of an object?
    • the shape
    • speed
    • direction
  2. what is the unit of force?
    newtons (N)
  3. what is the instrument used to measure forces?
    a Newton Balance
  4. what is the weight of an object?
    the force on it due to the Earth's gravitational pull
  5. what is the mass of an object?
    the amount of matter that makes up the object
  6. what is the gravitational field strength of a planet?
    the weight per unit mass of an object
  7. what is friction?
    a force that opposes the motion of an object
  8. what are three situations in which friction is increased?
    • applying the brakes of a car
    • opening a parachute
    • wearing rubber soled shoes for rock climbing
  9. what are three situations in which friction is decreased?
    • making racing cars streamlined
    • oiling moving parts in a car engine
    • using an air cushion on an air hockey table
  10. what are balanced forces?
    when equal forces act in opposite directions
  11. what is Newton's First Law of Motion in terms of seatbelts?
    • When a car brakes there is a force acting against the car slowing it down.
    • If the passenger was not wearing a seatbelt they would continue to move forwards at constant speed.
    • A seatbelt is therefore used to provide a backwards force to stop the
    • passenger from continuing to move forward at constant speed
  12. what is Newton's First Law of Motion?
    when balanced forces act on an object it remains at rest or continues to move at a steady speed
  13. what is Newton's Second Law?
    • When unbalanced forces act on a object the object changes speed.
    • The acceleration due to an unbalanced force depends on the mass of the object.
    • When the force stays constant and the mass increases, the acceleration decreases
    • When the mass stays constant and the force increases, the acceleration increases
Card Set
Transport: Forces at Work
Transport: Section 2- Forces at Work
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