NTNUJAVA Virtual Physics Laboratory
Enjoy the fun of physics with simulations!
Backup site http://enjoy.phy.ntnu.edu.tw/ntnujava/
December 10, 2018, 11:08:16 pm *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with username, password and session length
 
   Home   Help Search Login Register  
"Progress, therfore, is not and accident,¡K" ..."Herbert Spencer(1820-1903, British philosopher)"
Google Bookmarks Yahoo My Web MSN Live Netscape Del.icio.us FURL Stumble Upon Delirious Ask FaceBook

Pages: [1]   Go Down
  Print  
Author Topic: Fall and Rebound  (Read 8008 times)
0 Members and 1 Guest are viewing this topic. Click to toggle author information(expand message area).
Fu-Kwun Hwang
Administrator
Hero Member
*****
Offline Offline

Posts: 3080



WWW
«
Embed this message
on: June 13, 2010, 01:50:05 pm » posted from:Taipei,T\'ai-pei,Taiwan

Fall and Rebound
How do we simulate a (free) falling object?
Well, the answer, in principle, is rather simple: just solve the equation y'' = -g, where g is gravity.
And this works, perfectly well... except when the object reaches the ground. Then, we would expect the object to rebound.
When rebounding, the object changes instantly its velocity from downwards (negative) to upwards (positive). If the rebounding is perfectly elastic, then the object's velocity remains constant in modulus.
But, how would you implement this in a simulation?
This example shows two possible approaches to solve this problem.
The first one uses the closed form solution of the equations for the movement. It is fast, clean and efficient. But implies that we know the solution. In other, more complicated situations, we might not be able to solve these equations. For instance, if there is an external variable force applied to the falling object.
The second approach implies fine-tuning the way we solve numerically the second order differential equation at every moment. When the object comes closer to the ground, we ask the method to use a smaller time step. This provides a more accurate computation of the velocity the object had when reaching the ground.
The disadvantage is that the simulation seems to run slower at the critical moment. We try to compensate this, by asking Ejs to run faster!
Author : Francisco Esquembre 

 From an original idea from Taiwan Workshop on Ejs Date : March 2002

Embed a running copy of this simulation

Embed a running copy link(show simulation in a popuped window)
Full screen applet or Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop. This work is licensed under a Creative Commons Attribution 2.5 Taiwan License
  • Please feel free to post your ideas about how to use the simulation for better teaching and learning.
  • Post questions to be asked to help students to think, to explore.
  • Upload worksheets as attached files to share with more users.
Let's work together. We can help more users understand physics conceptually and enjoy the fun of learning physics!


* FallAndRebound.gif (3.31 KB, 365x277 - viewed 555 times.)
Logged
Pages: [1]   Go Up
  Print  
"Progress, therfore, is not and accident,¡K" ..."Herbert Spencer(1820-1903, British philosopher)"
 
Jump to:  


Related Topics
Subject Started by Replies Views Last post
Material strength: a free-fall experiment
Molecular Workbench
concord 0 11087 Last post August 21, 2005, 11:53:46 pm
by concord
Free fall and projectile motion
Kinematics
Fu-Kwun Hwang 0 17868 Last post July 25, 2008, 07:02:16 am
by Fu-Kwun Hwang
Free Fall modelling with Friction force F = k*v
Collaborative Community of EJS
lookang 0 9372 Last post November 26, 2008, 01:13:20 pm
by lookang
Trajectory of free fall with different initial speed
Examples for beginner who want to learn EJS
Fu-Kwun Hwang 0 6627 Last post February 10, 2010, 04:24:03 pm
by Fu-Kwun Hwang
MORE WIDE FALL LOW
Question related to Physics or physics related simulation
tesla2 1 1822 Last post December 14, 2014, 05:30:06 pm
by diinxcom
Powered by MySQL Powered by PHP Powered by SMF 1.1.13 | SMF © 2006-2011, Simple Machines LLC Valid XHTML 1.0! Valid CSS!
Page created in 0.095 seconds with 23 queries.since 2011/06/15