The voice of a person, who has inhaled helium, has a remarkably high pitch. Explain on the basis of resonant vibration of vocal cord filled with air and with helium.

Helium atom has 2 electrons in its valence shell but its valency is not 2. Explain.

Assertion : Male has deeper pitch of sound than female . Reason : At puberty , size of larynx and vocal cords increase in male .

The pipe closed at one end, has an air column. The air column is in resonance with a vibrating tuning fork of frequency f(75Hzltflt300Hz) . Length of air column is 93.75 cm find f (speed of sound in air is 330(m)/(s) )

A sonometer wire under tension of 63 N vibrating in its fundamental mode is in resonance with a vibrating tuning fork. The vibrating portion of that sonometer wire has a length of 10 cm and a mass of 1 g. The vibrating tuning fork isnow moved away from the vibrating wire with a constant speed and an observer standing near the sonometer hears one beat per second. Calculate the speed with which the tuning fork is moved if the pseed of sound in air is 300 m/s.

NASA is experimenting with balloons for use on ultralong duration (100 days) flight around the Earth. Consider a balloon that has the shape of a cylindrical chamber which is 35 m tall with 30 m radius, and is made of extremely light plastic. If our model cylindrical balloon is filled with helium gas, what is the mass of the maximum payload it could lift from the Earth's surface? (Given rho_(air)=1.29(kg)/(m^3) . rho_He)=0.18(kg)/(m^3) . Why would NASA design the balloon so large?

A sonometer wire under tension of 64 N vibrating in its fundamental mode is in resonance with a vibrating tuning fork. The vibrating portion of the sonometer wire has a length of 10 cm and mass of 1 kg. The vibrating tuning fork is now moved away from the vibrating wire with a constant speed and an observer standing near the sonometer hears one beat per second. Calculate the speed with which the tuning fork is moved, if the speed of sound in air is 300 m/s.

Two balloons of the same volume are filled wi t.h gases at the same pressure, one with hydrogen and the other with helium. Which of the two has the greater buoyancy (including the weight of the bag) and what is the ratio of buoyancies?