FORCES

FORCES

different forces
1. gravitational pull/weight
2. push
3. pull
4. friction
5. magnetic
6. electrostatic
7. bouyancy/upthrust
8. water resistance/drag
9. air resistance
10. electrical
11. nuclear
12. tension
13. lift
14. reaction (push and pull)
forces are shown through arrows. eg.
Newtons 1st law
1. An object stays what it is doing unless a bigger force overpowers the object
2. if an object is stationary it will remain stationary
  1. ie. balanced forces produce uniform motion
3. if the object is moving, it will continue to move at the same speed and the same direction
Newtons 2nd law
1. if the resultant force acting on an object is 0 then all forces are said to be unbalanced
  1. acceleration is indirectly proportional to mass
  2. acceleration is directly proportional to force
2. the speed of the object may change - it may either increase or decrease
3. the direction of motion may change
4. so an object will accelerate when the forces become unbalanced
5. force = mass x acceleration
  1. mass = force/acceleration
  2. acceleration = force/mass
  3. always use RESULTANT FORCE
Newtons 3rd law
1. if object a exerts a force on object b then object b exerts an equal but opposite force on object a
2. forces occur in action-reaction pairs
Resultant force
1. the vector sum or overall force of all the forces acting on an object is called the RESULTANT FORCE
2. eg. force of 5N -----OBJECT-----5N
  1. here the resultant force is 0N because the vector force to the left is cancelled out by the vector force to the right
3. the effect of resultant forces
FORCES THAT OPPOSE WEIGHT
1. if there is contact between two surfaces the force up is REACTION
2. If the object is lighter than the surroundings the force up is UPTHRUST/BUOYANCY
3. If the object is falling the force up is DRAG/AIR RESISTANCE
4. I we have an aeroplane or a helicopter the force up is LIFT

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	Created by Esme Poole over 10 years ago