Physics 8 - forces in balence

what is a scalar quantity ?

only has magnitude (size)

what is a vector quantity ?

has both direction and magnitude

what is a force ?

a push or pull that acts on an object due to the interaction with and other object

is force a vector or scalar quantity ?

vector

what is a contact force ?

when objects are physically touching - air resistance, friction

what is a non contact force?

when objects are physically separated - gravity, magnetic

what happens to the interaction forces when two objects interact ?

the forces are the same size but in opposite directions

turning effect of a force

moment

principle of movements

sum of anti-clockwise moments = sum of clockwise moments

how can a lever reduce the amount of force needed to create a particular sized moment ?

by increasing the distance form the pivot

what happens to a moment of a force when a small gear drives a large gear

moment is increased

newton’s first law

an object in motion stays in motion unless acted on by a force

what is the resultant force on a stationary object

zero

newton’s third law

every action has an equal and opposite reaction