Question

Please tell me what is this
I didn't undurstood this​

Answer 1

Answer:

I also don't know which class plz tell

Explanation:

Hope it helps you

Answer 2

Answer:

it is balance spring which is an essential adjunct to the balance wheel, causing it to oscillate back and forth. The balance spring and balance wheel together form a harmonic oscillator, which oscillates with a precise period or "beat" resisting external disturbances, and is responsible for timekeeping accuracy.