What does light mean?
= not heavy
= negligable mass - ignore mass
What does static mean?
= stationary
What does rough?
= friction
What does smooth mean?
= no friction
What does rigid mean?
= cannot be bent
What does thin mean?
= negligibley thick
What does particle mean?
= air resistance does not affect it
What does plane mean?
= flat surface
What does inextensible mean?
= does not stretch