Classical mechanics -- Equations for simulating the motion of a body

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SUMMARY

This discussion focuses on simulating the motion of a body using differential equations and kinematic principles. The user seeks to create a simulation in MATLAB that involves changing the direction of motion over time, specifically using piecewise continuous forces. Key insights include the use of kinematic equations for constant acceleration and the importance of understanding Newton's Laws of Motion and Free Body Diagrams (FBD) for accurate modeling. The conversation emphasizes the need for a dynamic model to effectively simulate the desired motion.

PREREQUISITES
  • Understanding of Newton's Laws of Motion
  • Familiarity with Free Body Diagrams (FBD)
  • Basic knowledge of kinematic equations for constant acceleration
  • Proficiency in MATLAB for simulation purposes
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  • Research MATLAB's capabilities for simulating dynamic models
  • Learn about piecewise continuous force applications in motion simulations
  • Study the implementation of kinematic equations in MATLAB
  • Explore advanced control systems for dynamic simulations
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Students and professionals in mechanical engineering, physics enthusiasts, and anyone interested in simulating motion dynamics using MATLAB.

s1mos_tsr
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Hello forum, i want to make a samulation of a body. The body will be moved horisontal on y,x axis. I want on my simulation the body to change direction many times(for example i want to go for 10sec right and then left end right...). My question is does i need more than one differential equation to describe this type of motion?
thanks in advance lovers of physics
 
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Hello @s1mos_tsr , :welcome: !

What causes the body to move/change direction ?
As a minimum you don't need a differential equation at all, just a prescription for the motion...
 
Lets say that the object has a inside mechanins to produce force, for example at t=0 a instand force make the object to move right and at t=10 a counterforce make the object to move left. In my mind i have a plan to make a dynamic model to have the simulation i don't know if this is the right method.
 
s1mos_tsr said:
Lets say that the object has a inside mechanins to produce force, for example at t=0 a instand force make the object to move right and at t=10 a counterforce make the object to move left. In my mind i have a plan to make a dynamic model to have the simulation i don't know if this is the right method.
Welcome to the PF. :smile:

Can you say a bit about your background so far in math and physics? Are you familiar with Newton's Laws of Motion?

https://en.wikipedia.org/wiki/Newton's_laws_of_motion

Are you familiar with drawing a Free Body Diagram (FBD) of an object to help in calculating the motion resulting from forces and torques ("moments") applied to the body?
 
I am studying mechanical engineering and i started a project about control systems. My project is to make a simulation on MATLAB of an inverted pendulum but because its a little bit deep for me i wanted to start a easier simulation on MATLAB like a free fall body and moving body on surface. My goal is to achieve the control the pendulum. I want also to make it more visual and try to animate the simulation. I have good background on statics systems but on the dynamics models i am not so good. My main question this moment what i said at the 1st post and also how to describe with maths the change of force that makes the body to change direction.
** at t=0 a instand force make the object to move right and at t=10 a counterforce make the object to move left
 
Last edited:
Well, if you use stepwise continuous vector forces, you can use the kinematic equations of motion for constant acceleration, which simplifies things a lot, right? Maybe start with that, and then later move on to discrete simulations of motion where the forces vary with time.

What would the motion of a 1kg mass be like given this piecewise continuous force profile?

##0s < t \leq 1s : F = 1N \hat x##
##1s < t \leq 2s : F = 3N \hat y##
## 2s < t \leq 3s : F = -2N \hat x##
 
Ok i think i get it a little bit. The point is to change the force(by changing the the sign) while the code is running at the time you want, correct me if i am wrong. But on the image i don't understand what N and X(hat) represents there.
 
##N## is Newton, SI unit of force (kg m/s2)
##\hat x## is a unit vector in the ##x##-direction
 

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