FORCES

Balanced and Unbalanced Forces

• Forces are measured in Newtons (N)
• a RESULTANT FORCE is made when several forces act on the same object
• A resultant force is the (vector) sum of the individual forces acting on the object

Forces between Objects

• Forces always act in (interactive) pairs
• these forces are the same size and acting in opposite directions
• they act on different objects and so CANNOT balance
• eg. weight of car pushing on the earth and earth pushing back on car

Resultant Forces

• Object at rest, resultant force zero; stays at rest
• moving object, resultant force zero; velocity stays same
• Moving object, resulatan force non-zero in same direction as direction of motion of object; accelerates
• Moving object, resultant force non-zero in opposite direction to direction of motion of object; decelerates

Mass, Weight and Gravitational Field Strength

• mass of object (kg)=quantity of matter in it
• weight of object (N)=force of gravity acting upon it
• on earth's surface gravity pills on 1kg mass with force…