Simple problem about relative motion.

AI Thread Summary
A body with two spheres connected by a 10-meter rod is rolling down one incline and up another at 45 degrees. At a specific moment, the downward sphere has a velocity of 2 m/s and an acceleration of 3 m/s². The discussion focuses on calculating the upward sphere's velocity and the rod's angular velocity using the equation VB = VA + ω × rB/A. Participants express confusion over the calculations and the proper application of vector components and angular velocity. Clarification is sought on the equations used and the interpretation of terms like "ez."
ParrotPete
Messages
6
Reaction score
0

Homework Statement


A body consisting of two spheres attached by a 10 meter solid long rod is rolling down a 45 degree incline at one end while rolling up a 45 degree incline on the other end.
At the instant when the connecting rod is horizontal the sphere rolling down has the velocity 2 m/s down the incline and the acceleration 3 m/s^2 down the incline. At this time, what is the velocity of the sphere rolling up and what is the angular velocity of the rod?

Homework Equations



VB = VA+ωXrB/A

The Attempt at a Solution


VA=2*(cos(45)*ei-sin(45)*ej
VB = VB*(cos(45)*ei+sin(45)*ej)
rA/B= 10*ei
ω=ω*ez
Doing the calculations
VB cos(45) = cos(45)
VB*sin(45) = -2*sin(45)+10ω

What am I doing wrong?
 
Physics news on Phys.org
ParrotPete said:
VA=2*(cos(45)*ei-sin(45)*ej
VB = VB*(cos(45)*ei+sin(45)*ej)
I guess that's VB = vB*(cos(45)*ei+sin(45)*ej), to avoid the pun.
rA/B= 10*ei
ek, perhaps?
ω=ω*ez
What's ez? Do you mean ei?
Doing the calculations
VB cos(45) = cos(45)
You've lost me - where did that come from?
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top