# Search results

1. ### Calculating new moment of inertia matrix with a new center of mass

woops, I left that out of the problem statement. from the base of the rocket, the cylinder that has the propellant is 1.5 ft. long. I just used then 7lbf for the propellant at CM of .75 ft to get the CM accociated with just the structure. Basically set up this.... [7(.75) + 16x]/23 = 2.6...
2. ### Calculating new moment of inertia matrix with a new center of mass

Homework Statement The total length of the composite body is 4.5 feet. Before the propellant is burned, the projectile weighs 23 lbf. After the propellant burns, the remaining projectile weighs 16 lbf. Before the propellant is burned, the mass center is located 2.6 feet from the projectile...
3. ### Difference between Crank-Nicolson and Peaceman-Rachford Schemes with ADI

Hi, I am in a numerical methods for PDE's class and have just been introduced to the ADI method. My teacher has given a general 2D heat equation to numerically compute using ADI with Crank-Nicolson and ADI with Peaceman-Rachford schemes. I understand what ADI is doing, I just don't know...
4. ### Neumann Boundary Conditions using FTCS on the Heat Equation

I am really confused with the concept of Neumann Boundary conditions. For the simple PDE ut=uxx for the domain from 0<=x<=1 I'm trying to use a ghost point (maintain a second order scheme) for the Neumann Boundary condition ux(0,t) = 0. I understand that I can setup a scheme to...
5. ### Direction of Forces on an Inclined Plane

yes, beta is a function of time. the problem statement is to find the equations of motion for the mass m hanging by a light string on an incline. both beta and theta change with time. i have already computed what the acceleration of the mass is as seen by the inertial frame. now, i need to...
6. ### Direction of Forces on an Inclined Plane

Because I only have one component of all these forces acting in my Km direction, can I say that the sum of the forces in that direction is equal to zero? Therefore, my N is just zero. Can a normal force even be zero?
7. ### Direction of Forces on an Inclined Plane

I'm supposed to find the equations of motion in terms of a given function beta and variable theta. the blue frame is inertial (I) and the other two frames are rotated reference frames. The frame I end up in is the green one (M) I already have the system to set up my acceleration a(M/I). Now...
8. ### Direction of Forces on an Inclined Plane

Homework Statement What are the directions of my forces acting on mass m with respect to my "m" frame (see attachment)? Homework Equations some trig and transformations maybe... The Attempt at a Solution I know I only have tension, weight, and a normal force acting on my particle but I...
9. ### Vector magnitude on an inclined plane - should be a quick answer

*distance vector magnitude "D"
10. ### Vector magnitude on an inclined plane - should be a quick answer

I don't have any dimensions. I'm asked to find the equation of motion of the point mass, so it's actually very involved (have three reference frames now). Maybe it ends up dropping out once I get everything set up. Should I just call that distance vector "D" for now and see what happens?
11. ### Vector magnitude on an inclined plane - should be a quick answer

Homework Statement Please see attachment. When θ = 0, mass m is at the bottom of the inclined plane. If I create a frame at origin O, with axes along the bottom of the plane and the dotted line (as shown in the picture), will my magnitude of the vector from O to A (along the dotted...
12. ### Equations of Motion for a mass on a circular track with a linear spring

Homework Statement A collar of mass m slides without friction along a circular track of radius R as shown in THE ATTACHMENT. Attached to the collar is a linear spring with spring constant K and unstretched length zero. The spring is attached at the fixed point A located a distance 2R from...