CH 4: Newton's Laws and Forces

Question 1

what is newtons first law

Answer 1

“An object at rest tends to stay at
rest, and an object in motion tends to remain in constant
motion, unless acted on by some net force.” meaning if theres a change in motion, means that theres a net force

Question 2

what is a (net) force

Answer 2

vectors
objs can only have one net force (sum of all forces)

Question 3

what is newtons second law

Answer 3

when there is a net force there is an accel., accel. is proportional to magnitude of net force,
& inversely proportional to the object’s mass
Fnet = ma

Question 4

whar is newtons third law

Answer 4

every force is actually a pair of forces
when an obj exerts on another obj, an equal and opposite force is being exerted back onto the first obj by the second obj
“For every action, there is an equal and opposite
reaction.”

Question 5

what are some typical forces encountered

Answer 5

Weight force – due to gravity (points toward center of Earth, “down”)
Normal force – due to a surface, always ⊥ (“normal”) to surface
Tension – a pulling force transmitted by a string, rope, chain, etc. (when drawing the arrow, imagine the direction where its being pull to/from)
static & kinetic friction – parallel to a surface – opposes motion

Question 6

what is weight force

Answer 6

w = mg