Answer:
The speed of the bob when it passes the lowest point 
Explanation:
Given data

When a pendulum swinging back & forth then at highest point the velocity is zero and lowest point velocity is maximum.
Velocity at lowest point is given by



Therefore the speed of the bob when it passes the lowest point 
The answer to this question is 2400Hz
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The problem was too big to type in my phone.
I hope my answer is readable.
P.S After the collision P is also moving in the same direction as Q.
Answer:
When two magnets are brought together, the opposite poles will attract one another, but the like poles will repel one another. This is similar to electric charges. Like charges repel, and unlike charges attract.