एक सरल लोलक (simple pendulum) 2 सेकंड में एक पूर्ण दोलन (आवर्तकाल) पूरा करता है। इसके दोलन की आवृत्ति (frequency) क्या है?

In an open organ pipe, v3 and v6 are the 3rd and 6th harmonic frequencies, respectively. If v6 − v3 = 2200 Hz, then the length of the pipe is ______ mm. (Take velocity of sound in air as 330 m/s.)

There is a second's pendulum on the surface of the earth. It is taken to the surface of a planet whose mass and radius are twice that of the earth. The period of oscillation of this second's pendulum on the planet will be: