Solve Rotational Motion Homework: Pulleys A, B, C

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SUMMARY

The discussion revolves around solving a rotational motion homework problem involving compound and contact pulleys A, B, and C. The user initially struggled with the lack of acceleration information and attempted to use the formula s = rδ to find angular displacement. After receiving guidance, the user successfully solved the problem by determining the linear acceleration of weight D, which was crucial for finding the correct answers for gears B and C.

PREREQUISITES
  • Understanding of rotational motion concepts, specifically angular and linear velocity.
  • Familiarity with pulley systems, including compound and contact pulleys.
  • Knowledge of kinematic equations related to rotational motion.
  • Ability to apply formulas such as s = rδ in practical scenarios.
NEXT STEPS
  • Study the principles of linear acceleration in pulley systems.
  • Learn how to apply kinematic equations to solve complex rotational motion problems.
  • Explore the differences between compound and contact pulleys in detail.
  • Practice problems involving angular displacement and velocity calculations.
USEFUL FOR

Students studying physics, particularly those focusing on mechanics and rotational motion, as well as educators looking for examples of pulley systems in action.

freshbox
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Homework Statement


Attached 1st pic is the question, 2nd pic is the formula

PS: I am sorry if i have posted on the wrong section.

The Attempt at a Solution


My understanding for this question is for compound pulley, angular velocity is the same, linear velocity is different. For pulleys in contact, linear velocity is the same and angular velocity is different.

Since in this case, A/B are compound pulleys whereas B/C are contact pulleys.
But the question did not give me any acceleration info on any of the pulleys, so I don't know where to start..

The only info that I can gather is:

ωi=0m/s²
s=17m
t=20s

So I tried to use s=rδ formula.
17=0.15δ
δ=113.33

Although I managed to get "1" of the answer, but the info I used was all from pulley A but the answer they want is gears B/C so I'm abit confused here.
Hope someone can help me out.Thanks.
 

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welcome to pf!

hi freshbox! welcome to pf! :smile:
freshbox said:
… the question did not give me any acceleration info on any of the pulleys, so I don't know where to start..

start by finding the (linear) acceleration of the weight D :wink:
 
Hi tiny-tim thanks for the tip, i solved the problem already :)
 

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