Chapter 1 - Monentum and Impulse Flashcards
Instantaneous Momentum
In real life, no object has constant momentum because it’s velocity is usually not constant.
Friction opposes the motion of all objects and eventually slows them down. Thus it is more accurate to say instantaneous momentum: momentum at a specific instant.
Relating Momentum to Newtons Second Law
Fnet=ma
=m(vf-vi/t)
*distribute the m
= (mvf-mvi)/t
*mv is equal to momentum
= (pf-pi)/t
Fnet= change in momentum/change in time
Fnet is a constant
➖➖➖➖➖➖➖➖➖➖➖➖➖
If net force changes over a time interval, the average net force is equal to the rate of change of the object:
Fnet(average)= change in momentum/change in time
What does it mean to give an object momentum?
You’re applying a force for a given period of time to change its motion/momentum
Impulse
Equal to the change in momentum of the object
Impulse is a product of the NET FORCE acting on an object over a specific TIME
Causes a change in the momentum of the object
Momentum
mass of an object x velocity
(p=mv)
directly proportional to mass and velocity
Newtons Second Law in relation to Impulse
Fnet=ma
*accelaration is equal to velocity over time
Fnet=m(v/t)
*distribute the mass into the equation
Fnet=(m🔺vf-m🔺vi)/t
*mass times velocity equals momentum
Fnet=(pf-pi)/t
*move the time over to the other side
Force x time = pf-pi
F x T = 🔺p
- This formula shows us that impulse (f x t) is equal to momentum
Units for Momentum
kg x m/s
Is impulse a vector
YES!!
What are the units for impulse ?
N x S
newtons times seconds
What happens when a putty ball hits a SOFT surface?
The more cushioned a surface, the more it indents when the putty hits it.
A softer surface provides MORE STOPPING DISTANCE, because the surface moves from a normal flat position to moving with the putty (downwards) to provide a force against it.
How do you stop changes to the shape of an object being dropped ?
MINIMIZE FNET
MAXIMIZE TIME
Impulse Momentum Theory
the CHANGE IN MOMENTUM of an object EQUALS THE IMPULSE APPLIED
J = 🔺P = FxT
Impulse and Net Force Time Graphs
The slope DOES NOT MEAN ANYTHING!!!
The area under the line is multiply force and time, therefore :
The are is equal to the impulse acting on the object.
Force= y axis Time= x axis
Collision
interaction between two objects where each receives an impulse
What is a System
two or more objects that interact with each other
