newtons first law
an object in motion won't change its motion unless what?
unless it is acted upon by a net force
vectors have a what
a direction
forces always come in what?
pairs
Is friction nessesary for cars on the road? explain
yes so that the car will go and stop
a skydiver accelerating downward
unbalenced
a non zero net force will change the what?
velocity
the greater the force, the greater the?
acceleration
for every action force there is what?
an equal and opposite reaction force
what is friction?
Friction is the force resisting the relative motion of solid surfaces
a cannonball fired parallel to the ground
unbalenced
a net force is not required to maintain the what?
velocity
an object will accelerate in the direction of the what
net force
if the earth pulls on the satellite what will happen?
the satellite will pull on the earth as well
pushing you hands together while rubbing them quickly will create what?
heat
a motorboat coasting at a constant speed
balenced
if an object is stationary the external forces are all what
balanced
the magnitude of acceleration is proportional to the what
the force
when a heavy and light football player run into each other, who exerts more force?
the light player will
what is friction determined by?
surface roughness, force pushing objects together, and surface area
a bike leaning agiainst a tree
balanced
external forces change the motion not the what?
internal forces
what is the magnitude of the acceleration inversely proportional too?
the mass
you hit a wall with a stick. the equal but opposite reaction is what?
the wall pushes against the stick
friction does what?
opposes motion between objects that are in contact
since balanced forces have a net force of zero they do not effect what?
the motion of the object