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Two blocks $$A$$ and $$B$$ of same mass $$M$$ are connected with each other with an ideal string of length $$2l$$ passing over an ideal pulley. The block $$A$$ is connected to a light pan $$C$$ with an ideal string as shown in figure. A particle of mass $$\frac{M}{2}$$ is dropped on pan from height $$\frac{l}{2}$$ as shown. If collision between particle and pan is plastic, acceleration of $$B$$ just after the collision is?

Ans is $\frac{g}{9}$.

Is this solution correct?

Note by Nishant Rai
2 years ago

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My Answer is a little different..

· 1 year, 11 months ago

I think you guys would like to see this discussion. · 2 years ago

Although your answer is correct, the FBDs that you have drawn are not. You have missed out the gravitational force on $$A$$. Due to this reason, you have skipped using $$T_1 -Mg=Ma$$

In reality, at the moment the mass strikes the pan:

$$T_1 = Mg + M\frac {v^2}{l}$$

And hence: $$T_1 -Mg=Ma=M\frac {v^2}{l}$$

Otherwise, you can also use constraint relations to get to same result. · 2 years ago

I have a confusion. I think it is assumed that just after the collision block A performs a circular motion. But as soon as the block a A gets a tangential velocity it would have centripetal as well as a radial acceleration. How can we ignore that? · 2 years ago

Raghav Vaidyanathan

i have done the same thing, (this solution is not mine, this question came in mock paper of some coaching institute, they have provided this solution) · 2 years ago

Okay, but they aren't fully wrong, we can get everything without FBD itself... · 2 years ago

btw you are appearing for JEE ? are you enrolled in any coaching institute? · 2 years ago

Yes, FIITJEE · 2 years ago

Can you please post the solution to Angular width of Refracted Beam!

Raghav Vaidyanathan · 2 years ago

ok · 2 years ago

@satvik pandey i have made a note on this problem inviting views of other brilliant members(bc now even i am confused :/ ) · 2 years ago

Thanks for making it! :) · 2 years ago

Why wasn't $$T_1$$ impulsive.😓 · 2 years ago