what is force

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  • 1. What is Force?
    • 1) Force is a push or pull
    • 2) Force is the capacity to do work or cause physical change
    • 3) Force= Mass times acceleration (F = ma)
    • 4) A force is that which changes or tends to change the state of rest or motion of a body.


  • A. Contact Forces :
  • 1. frictional force(friction)-
  • caused by the rubbing of two objects.

3. 2. buoyant force(buoyancy)-it is the upward force of fluids on floating objects. 3. normal force-is the support force on an object which is in contact with another stable object. 4. air resistance force- type of frictional force upon objects as they travel through the air. 4.

  • 5.Tension force- is the pulling force through a string, rope, cable or wire.
  • 6.Spring force- is the force exerted by a compressed or stretched spring upon any object which is attached to it .
  • 7.Applied force- is a force which is made to an object by a person or another object.


  • B. Action-at-a-distance forces:
  • 1. gravitation-is the force with which the earth, moon, or other very large object attracts another object towards itself.
  • 2. Electrostatic force is the force between particles that are caused by their electric charges.
  • Electric force-
  • 3.magnetic forces is the force made between magnetic poles


  • Common Units of Force
  • --->> SI :Newton (N)1 N = 0.225 lb;
  • One Newton (N) of force is defined as the amount of force needed to accelerate 1 kilogram (kg) of mass at a rate of 1 meter per second squared (m/s2).
  • 1 Newton = 1 kg m/sec2(A kilogram is the amount of weight at which 1 N of force will accelerate at a rate of 1 m/s2.)


  • A force is avector quantity .
  • Avector quantityis a quantity which has bothmagnitudeanddirection.
  • Example:10 Newtons, downwards
  • 25 km,east
  • Ascalar quantitycan be described using only 1 quantity, magnitude.
  • Examples:time, energy,volume,temperature.


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