3.5 newtons laws of motion and momentum Flashcards
what is newtons first law
an object will remain stationary or at a constant velocity unless acted on by a resultant force
what is newtons second law
force is directly proportional to the rate of change of momentum, and acts in the same direction
what is newtons third law
if object A exerts a force on object B then object B exerts an equal and opposite force of the same type on object A.
does momentum have an associated direction
yes, so you have to include + or - to signify direction
when can you not use F=ma
when mass is not constant
is momentum always conserved
yes, momentum before= momentum after
in which type of collision is kinetic energy not conserved
inelastic collision
in which type of collision is kinetic energy conserved
elastic collision
what is the equation for kinetic energy
KE=½mv²
what is impulse
change in momentum
what is the symbol for impulse
F∆t
what is the equation for momentum
momentum = mass × velocity (p=mv)
what does the area under a force- time graph represent
change in momentum = impulse
if you cannot remember the symbol for impulse which equation can you derive it from and how do you get it
F=∆p÷∆t (rearrange do that you get it equal to the change in momentum (∆p) as that’s the definition for impulse)
what is an objects final velocity equal to if it rebounds perpendicularly off a wall
-u (as its equal and opposite like newtons 3rd law)
what is the change in momentum equal to
final momentum - initial momentum
when is a collision oblique
when an object does not centrally collide with another
in an oblique collision what direction do the objects go in
perpendicular (90°)
to solve an oblique collision (work out a force) what do you do
draw a force diagram (triangle)
what direction do all rebound collisions go from the surface
90° (perpendicular)
to calculate the overall force on the wall is has to be parallel or perpendicular so what do you do to fix this
you resolve it (trigonometry)
