3. Let the pen return to its vertical position and suddenly pull the thread. Q4. What happened to the thread tied on the pen?

The thread will experience a force on it .

Explanation:

When thread is tied to pen it will experience force. Because the pen is Abit heavy , there is a force that is applied to it which will cause it to elongate , after a while the thread will stretch, elongate and can later experience deformation. When it experience that, the thread can break after deformation and it has losses it elasticity.

answer: pseudoscience

this is poiselle's equation from fluid mechanic in physics. mech eng