Trajectory of projectile with considerable drag

AI Thread Summary
The discussion focuses on solving the trajectory of a projectile with drag proportional to v^2, leading to a set of coupled differential equations. The equations describe the motion in terms of velocity, angle, and position, with initial conditions provided. Participants emphasize the importance of choosing a consistent coordinate system for solving the equations. There is a request for assistance in solving the mathematical aspects of the problem, despite previous attempts to find solutions. The conversation highlights the complexity of the equations and the need for guidance in tackling such differential equations.
HP007
Messages
3
Reaction score
0
Facing some horrible mathematical situation while solving to find equation of trajectory of projectile when drag is proportional to v^2.
my equations where i end up with are as follow:
equation 1:
mdv/dt=(-kv^2)+(-mgsinγ);
equation 2:
(-mv)dγ/dt=mgcosγ;
equation 3:
dx/dt=vcosγ;
equation 4:
dy/dt=vsiny;
where:
v is velocity of particle at instance when it makes an angle γ with horizontal plane.
Initial condition is known and assume it to be u at an angle α.
please assist me in solving this.
 
Physics news on Phys.org
(1) ##m\dot v = -kv^2-mg\sin\gamma##
(2) ##-mv\dot \gamma = mg\cos\gamma##
(3) ## \dot x = v\cos\gamma##
(4) ## \dot y = v\sin\gamma##

Whence ##v(0)=u## and ##\gamma(0)=\alpha##

Do you want the trajectory: (x(t),y(t))?

Have you ever tried to solve systems of differential equations before?
(i.e. what is the level of education help should be aimed at?)

Have you seen:
http://users.df.uba.ar/sgil/physics_paper_doc/papers_phys/mechan/air0.pdf

You seem to be trying to use cartesian and some sort of polar coordinates at the same time - it is best practice to pick just one coordinate system and stick to it.
 
Last edited by a moderator:
Nugatory said:
This problem has come up before. Try this thread: https://www.physicsforums.com/showthread.php?t=712807


But I have already arrived at those set of coupled equations I want to know the way to solve it.
Assist me in solving mathematical part of the problem.
 
The rope is tied into the person (the load of 200 pounds) and the rope goes up from the person to a fixed pulley and back down to his hands. He hauls the rope to suspend himself in the air. What is the mechanical advantage of the system? The person will indeed only have to lift half of his body weight (roughly 100 pounds) because he now lessened the load by that same amount. This APPEARS to be a 2:1 because he can hold himself with half the force, but my question is: is that mechanical...
Some physics textbook writer told me that Newton's first law applies only on bodies that feel no interactions at all. He said that if a body is on rest or moves in constant velocity, there is no external force acting on it. But I have heard another form of the law that says the net force acting on a body must be zero. This means there is interactions involved after all. So which one is correct?
Thread 'Beam on an inclined plane'
Hello! I have a question regarding a beam on an inclined plane. I was considering a beam resting on two supports attached to an inclined plane. I was almost sure that the lower support must be more loaded. My imagination about this problem is shown in the picture below. Here is how I wrote the condition of equilibrium forces: $$ \begin{cases} F_{g\parallel}=F_{t1}+F_{t2}, \\ F_{g\perp}=F_{r1}+F_{r2} \end{cases}. $$ On the other hand...
Back
Top