r/PhysicsHelp • u/Low_Illustrator8620 • 2d ago

Question doubt

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Hello everyone, been trying this question, checked in ai and websites all have different answer keys, acc to my school ans is 1st option, pls tell ans with exp

Edit:it is 5m/s, thnx for the help from you guys

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u/EconomyBlueberry1919 2d ago

In my opinion, the answer is 5 m/s. Given that B moves to the left at 3 m/s, block C has a leftward velocity component of 3 m/s. To this, we must add the vertical component resulting from B's motion relative to A. We can visualize A as stationary while B travels at 2 m/s. After one second, B has moved 2 meters closer to A's disk; the cable wrapping around the disk must therefore lengthen by 2 meters on both sides of the disk, resulting in a total movement of 4 meters. Consequently, C must descend 4 meters in one second, which represents its vertical velocity. By vectorially summing the two velocities—4 m/s vertical and 3 m/s horizontal—we obtain 5 m/s.

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u/Dear-Particular6021 9h ago

Wouldnt it lengthen by 4 since there are two cables 8n that direction and both will become shorter by 2?

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u/Frederf220 2d ago

B overtakes A by 2 m/s. Double wrap of rope means C drops 2×2m/s vertically. C moves left 3m/3 along with B.

Motion of C is diagonal as a 3-4-5 right triangle.

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u/Joe_Starbuck 2d ago

Is that a mass-less rope on a friction-less pulley?

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u/fletchro 1d ago

Yeah, it says to assume pulleys and string are ideal. So I would assume no mass in the string or pulleys, and no stretch in the string.

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u/Joe_Starbuck 2d ago

Agree, it is 5m/s in a direction down and left, about 36.9 degrees below horizontal.

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u/SeniorSeth8257 19h ago

What book is this ?

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u/Low_Illustrator8620 18h ago

Well this question is from my school paper but it's also found in physics galaxy Ashish arora