How Does the Ceiling Exert Force on a Pulley System?

AI Thread Summary
The discussion centers on calculating the force exerted by the ceiling on a hook supporting a pulley system with two weights, 75 N and 125 N, connected by a cord over a frictionless pulley. The total force exerted by the ceiling is determined to be 249 N. The participants emphasize applying Newton's second law to analyze the forces acting on both weights and the pulley. The tension in the rope sections is noted to differ, which is crucial for the calculations. Overall, the problem illustrates the dynamics of a pulley system and the resultant forces involved.
J89
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Homework Statement



Two weights are connected by a very light flexible cord that passes over a 50 N frictionless pulley of radius .300 m. Pulley is a solid uniform disk and is supported by a hook connected to a ceiling. What force does the ceiling exert on the hook? There are two weights around each side of the disk, one is 75 N and the other is 125 N. Answer is 249 N.


Homework Equations



I = 1/2 MR^2
F=ma




The Attempt at a Solution

 

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J89 said:
Two weights are connected by a very light flexible cord that passes over a 50 N frictionless pulley of radius .300 m. Pulley is a solid uniform disk and is supported by a hook connected to a ceiling. What force does the ceiling exert on the hook? There are two weights around each side of the disk, one is 75 N and the other is 125 N. Answer is 249 N.

Hi J89! :smile:

(I assume that "frictionless pulley" means that there is friction between the pulley and the rope, with no slipping)

The tension in the two sections of rope will be different … call them Tm and TM, and call the linear acceleration a …

then apply good ol' Newton's second law three times, ie to each of the weights and the pulley (separately), to get Tm + TM :wink:
 

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