topic 3: dynamics

length of arrow is proportional to

magnitude of force

net force =

vector sum of all forces acting on object

SI unit of force

Newton

SI base unit of force

kgms^-2

contact force

act when 2 interacting objects have physical contact with each other

non-contact force

forces that act over a distance without physical contact between two interacting object

weight

force of gravity acting on a body

mass

amount of matter in a body

mass is measured by

electronic mass balance

weight is measured by

calibrated spring balance

weight =

mass x gfs

the larger the mass of the body

the greater resistance to resist change in its motion

inertia

resistance of a body to resist change in the state of rest or motion of the body

normal contact force

the perpendicular force exerted by the surface of one object on the surface of another when they are in physical contact

ncf is always (…) to the surface

perpendicular

ncf always passes through

point of contact

frictional force

contact force that acts between object that opposes motion

frictional force is proportional to

ncf and nature of the contact surfaces

vicous force

resistive force for solids moving in fluid

viscous force is directly proportional to

speed and surface area

tension

force exerted by a flexible objext on another object

tension always exerts

a pull, never a push

tension is always directed

away from the string, along the length of the string

N1L

A body will remain in its state of rest or uniform motion in a straight line unless acted upon by a resultant force

N2L

The resultant force acting on an object of constant mass is the product of the mass and acceleration of the object. The object accelerates in the direction of the resultant force.

Fnet

= mass x acceleration

N3L

If body A exerts a force on body B, then body B exerts an equal and opposite force on body A

action-reaction pair forces must be

of the same type

action-reaction pair forces act on

different bodies

action-reaction forces are equal

in magnitude

action-reaction forces are opposite

in direction