# 0.24 Phy1215: energy -- elastic and inelastic collisions in two  (Page 4/9)

 Page 4 / 9

Having done that, you can rotate the axis by the same amount in the opposite direction at the end to cause the final solution to apply to the original axes.I will present an example of this in the next section.

## Example scenarios

Several examples

I will use the information in Figure 1 to analyze several scenarios involving collisions in both one dimension and two dimensions in this section.

The use of JavaScript

All of these examples could be solved using the Google calculator. However, several steps are involved and I find it easier to keep things organized andperform the steps in the correct order by using JavaScript to compute and display the solution.

Note, however, that JavaScript will only do the arithmetic for you. You must still do the algebra/trigonometry yourself. In these examples, I willusually work through the algebra in comment sections and switch to actual code when it is time to compute and display one or more values.

## One-dimensional scenarios

The first one-dimensional scenario involves an automobile accident.

## The rear end car crash

The description as well as the solution to the problem are shown in Listing 1 .

Listing 1 . The rear end car crash.
```<!---------------- File JavaScript01.html ---------------------><html><body><script language="JavaScript1.3">/* This script simulates car #2 rear-ending car #1 in aone-dimensional elastic collision while car #1 was stopped. The script computes and displays the speed of car #2immediately before the collision under the assumption that car #1 was moving at 20 m/s just after the collision.Using conservation of momentum alone, we have two equations, allowing us to solve for two unknowns.m1*u1x + m2*u2x = m1*v1x + m2*v2x m1*u1y + m2*u2y = m1*v1y + m2*v2yUsing conservation of kinetic energy for the elastic case gives us one additional equation, allowing usto solve for three unknowns. 0.5*m1*u1^2 + 0.5*m2*u2^2 = 0.5*m1*v1^2 + 0.5*m2*v2^2Variables: m1, m2, u1, u2, v1, v2, a1, a2, b1, b2*/ document.write("Start Script</br>"); //Solve for u2 and v2 for an elastic collisionvar m1 = 1500;//kg var m2 = 2000;//kg//Velocities before the collision var u1 = 0;//meters per second - standing stillvar u2;//unknown value to be determined //Velocities after the collisionvar v1 = 20;//meters/second var v2;//unknown value to be determined//Angles var a1 = 0;//car was not movingvar a2 = 0;//moving straight ahead var b1 = 0;//moving straight aheadvar b2 = 0;//moving straight ahead //Convert angles to radiansA1 = a1*Math.PI/180; A2 = a2*Math.PI/180;B1 = b1*Math.PI/180; B2 = b2*Math.PI/180;//Compute and print the x and y components of velocity u1x = u1*Math.cos(A1)u1y = u1*Math.sin(A1) //u2x = u2*Math.cos(A2)//unknown//u2y = u2*Math.sin(A2)//unknown v1x = v1*Math.cos(B1)v1y = v1*Math.sin(B1) //v2x = v2*Math.cos(B2)//unknown//v2y = v2*Math.sin(B2)//unknown document.write("x and y components of velocity</br>"); document.write("u1x = " + u1x.toFixed(3) + "</br>"); document.write("u1y = " + u1y.toFixed(3) + "</br>"); document.write("v1x = " + v1x.toFixed(3) + "</br>"); document.write("v1y = " + v1y.toFixed(3) + "</br>"); document.write("==============================="+ "</br>"); /*Prepare the equations for use in solving the problem. Given the following three equationsm1*u1x + m2*u2x = m1*v1x + m2*v2x m1*u1y + m2*u2y = m1*v1y + m2*v2y0.5*m1*u1^2 + 0.5*m2*u2^2 = 0.5*m1*v1^2 + 0.5*m2*v2^2 Eliminate all of the components for which the above printoutshows zero or for which the given values show zero. 0 + m2*u2x = m1*v1x + m2*v2x0 + m2*u2y = 0 + m2*v2y 0 + 0.5*m2*u2^2 = 0.5*m1*v1^2 + 0.5*m2*v2^2Although it isn't totally obvious from the equations, at this point we need to recognize that because all velocities aredefined to occur along the x-axis, all of the terms in the middle equation above that deals with the y-component ofvelocity must be zero. Therefore, we can eliminate that equation entirely.We also need to recognize that because there are no velocity components along the y-axis, the velocity components alongthe x-axis are actually the magnitudes of those velocity components. Thus, u2x = u2.Now we will make the substitutions and eliminate terms with a value of 0 in the process, yieldingm2*u2 = m1*v1 + m2*v2 0.5*m2*u2^2 = 0.5*m1*v1^2 + 0.5*m2*v2^2Substituting known values into the two equations yields 2000*u2 = 1500*20 + 2000*v22000*u2^2 = 1500*20*20 + 2000*v2^2 Simplifying the two equations yieldsu2 = 15 + v2 u2*u2 = 300 + v2*v2Now we need to eliminate one equation through substitution v2 = u2 - 15u2*u2 = 300 + (u2 - 15)*(u2 - 15) u2*u2 = 300 + u2*u2 - 30*u2 +225u2*u2 - 300 - u2*u2 + 30*u2 -225 = 0 u2*u2 - u2*u2 + 30*u2 - 300 -225 = 030*u2 - 525 = 0 30*u2 = 525*/ //Compute and print the first speed valuedocument.write("Speed values</br>"); u2 = 525/30;document.write("u2 = " + u2.toFixed(2) + " m/s</br>"); /*Substituting this value back into an earlier energy equation yieldsv2*v2 = u2*u2 - 300; *///Compute and display the second speed value v2 = Math.sqrt(u2*u2 - 300);document.write("v2 = " + v2.toFixed(2) + " m/s</br>"); document.write("==============================="+ "</br>"); //Check the answers for conservation of momentumdocument.write("Check for conservation of momentum</br>"); var mou = m1*u1 + m2*u2;var mov = m1*v1 + m2*v2; document.write("mou = " + mou.toFixed(0) + " Kg*m/s</br>"); document.write("mov = " + mov.toFixed(0) + " Kg*m/s</br>"); document.write("==============================="+ "</br>"); //Check the answer for elastic collisionvar keIn = 0.5*m1*u1*u1 + 0.5*m2*u2*u2; var keOut = 0.5*m1*v1*v1 + 0.5*m2*v2*v2;document.write("Check for conservation of energy</br>"); document.write("keIn = " + keIn.toFixed(0)+ " Kg*m^2/s^2</br>"); document.write("keOut = " + keOut.toFixed(0)+ " Kg*m^2/s^2</br>"); document.write("End Script");</script></body></html>```

#### Questions & Answers

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
Do somebody tell me a best nano engineering book for beginners?
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
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.
what is nano technology
what is system testing?
preparation of nanomaterial
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
what is system testing
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
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