Moment of Torque; Am I solving this correctly?

  • Thread starter Thread starter vinci
  • Start date Start date
  • Tags Tags
    Moment Torque
AI Thread Summary
The discussion revolves around calculating the torque produced by two 30N forces acting on a 90cm metal rod with a disc at its center. The torque of the couple is calculated as 2700 Nm, which is derived from the distance between the forces and their magnitude. To prevent rotation, the tension in the rope attached to the disc must equal the torque produced, leading to a calculated tension of 112.5 N. Participants emphasize the importance of including units in calculations for clarity. The calculations presented are confirmed as correct, providing reassurance to the original poster.
vinci
Messages
12
Reaction score
4

Homework Statement


A metal rod of length 90cm has a disc of radius 24cm fixed rigidly at its centre(refer to picture attached). The assembly is pivoted at it's centre.
Two forces, each of magnitude 30N, are applied normal to the rod at each end so as to produce a turning effect on rod. A rope is attached to the edge of the disc to prevent rotation
1-Calculate the torque of couple produced by the 30N forces
2-the tension T in the rope
ametalrod.png

Homework Equations


Torque= moment arm * force applied perpendicular to pivot
torque of couple=distance between two forces * one of the force
(I assume the above equations will be relevant)

The Attempt at a Solution


For the rod the torque of couple would be
30 * 90 =2700

Now since the rotation is to be prevented by the disc in center it has to produce an equal torque in the opposite direction(anti-clockwise direction) so the torque produced by disc should also be 2700
and since
torque=moment arm*force applied
=radius*tension in string
2700= 24 * T
T=2700/24Have I solved the above numerical correctly? Since the book doesn't provide answer to these questions and I have no tutor I have no other way to confirm my calculations.
 
Physics news on Phys.org
That looks real good. Well done.
 
That's all fine, except that you really should state the units everywhere.
 
Thanks, everybody. That's a relief.
Secondly, I'll make sure to mention the units from here on.
 
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 'Collision of a bullet on a rod-string system: query'
In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
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