chapter 9 Flashcards
what is a collision
it is a short duration interaction between two objects
what is an impulse force
it s a large force exerted in a short interval of time
when is the impulse force applied?
it is applied only when the objects are in contact
what is the impulse force proportional to?
it is proportional to the area under the force vs time curve
what type of quantity is the impulse?
it is a vector
what direction does the impulse point?
it points in the same direction as the force
things with more mass have more what?
more inertia
what is momentum?
the quantity of motion of a moving body, measured as a product of its mass and velocity.
it is a measure of how hard it is to stop something from moving
if we exert an average impulse force to an object, what happens to its velocity?
it will accelerate
what is the impulse equal to?
it is equal to the change in momentum (pf-pi)
how is momentum calculated?
it is the product of the objects mass and velocity
what type of quantity is momentum?
it is a vector quantity that can be broken into components
what direction does momentum point?
it points in the direction of the velocity
what is the impulse momentum theorem?
it states that an impulse delivered to an object will cause the object’s momentum to change
if the duration of the collision is increased, what happens to the average force of impact
it will decrease
if it takes a longer amount of time to slow an object down, what happens to the force?
a smaller force is exerted in the collision
what is total momentum
it is the vector sum of all the momentum’s in the system of particles
what does the impulse approximation state?
it says that we can ignore small external forces that act outside of the system
what type of internal forces exist in a collision
action-reaction pairs that cancel each other out
what does the law of conservation of momentum say
it says that, in an isolated system, there is no change in the total momentum and the initial momentum is equal to the final momentum because the internal forces are action reaction pairs that cancel out
what are internal forces
internal forces are forces that act between the particles in a system (they are action reaction pairs and cannot change momentum)
what are external forces
they are forces that occur from agents outside of the system and can change the momentum
since momentum is a vector, what do we need to do when resolving 2D problems
we need to break it into components
what type of system do we want to choose
we want to choose one where the momentum is conersved
what is an explosion
it is when the particles of a system move apart after a brief interaction
if an explosion is isolated, what happens to the momentum
the momentum is conserved
what are perfectly inelastic collions
they are collisions in which the two objects stick together and move with a final common velocity
when calculating the momentum we add the masses (m1+m2) and multiply it by the final velocity
what is angular momentum?
it is how hard it is to get something to stop rotation
is momentum conserved for a spinning object?
no the momentum is not conserved because the direction changes due to the net torque, however, the angular momentum can be conserved
what does the conservation of angular momentum say
it says that if the net external torque is zero, the angular momentum will be conserved
how do we calculate the angular momentum?
it is the moment of inertia multiplied by the angular velocity
