0.18 Phy1160: force and motion -- momentum, impulse, and conservation  (Page 3/14)

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Proportional to both mass and velocity

From the above equation , it can be seen that an object can have a large momentum if either its mass or its velocity is large. Bothvariables are of equal importance in determining the momentum of an object.

A car and a tennis ball

Consider the case of a car and a tennis ball rolling down the street at the same speed. Because the car has greater mass, it has more momentum than thetennis ball. However, if the car stops and the tennis ball continues to roll, the tennis ball then has the greater momentum.

Momentum is zero at rest

The momentum of any object at rest is zero. Objects at rest do not have momentum because their mass is not in motion.

The quantity of momentum

The quantity of momentum possessed by an object depends on:

• How much mass is moving, and
• How fast the mass is moving.

For example, a small mass moving very fast can have the same momentum as a large mass moving slowly. You sometimes hear about the major damage that avery small piece of space junk moving at a very high speed could do if it were to strike the International Space Station.

A bullet shot from a firearm has a very small mass, but it has a very high velocity. Consequently, it probably has more momentum than a baseball pitchedfrom second base to home plate, even though the baseball has much more mass.

What happened to the dinosaurs?

Similarly, you may have heard that an asteroid with a mass that was small relative to the mass of the earth but with an extremely high velocity led to theextinction of the dinosaurs about 160 million years ago when it collided with the earth in the Gulf of Mexico.

Impulse

Momentum can be changed by a force

An object with momentum can be stopped if a force is applied against it for a given amount of time. For example, when a car approaches a red traffic light,the driver applies the brakes. The friction of the tires on the pavement applies a force to the car, which eventually reduces the car's velocity to zero. When thevelocity goes to zero, the momentum also goes to zero.

Therefore, the momentum of an object can be changed by applying a force to the object over a given period of time.

Unbalanced forces cause acceleration

As you learned in earlier modules, an unbalanced force always accelerates an object, either causing the object to speed up or causing the object to slowdown. Either way, the application of an unbalanced force to an object will change the velocity of the object. When the velocity of the object is changed, the momentumof the object is changed as well.

The impulse

Let's use what we know from Newton's second law to derive a concept known as impulse .

The product of mass and acceleration

You learned in an earlier module that force is equal to the product of mass and acceleration:

F = m * a

where

• F represents Force
• m represents mass
• a represents acceleration

The rate of change of velocity

You also learned that acceleration is the time rate of change of velocity, or

a = (v2 - v1)/t

where

• v2 - v1 indicates a change in velocity during a time interval given by t.

anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
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