The answer is D. Sound insulators prevent sound from being transmitted better than elastic solids because sound insulators basically muffle and block the sound waves.
The average speed would be 0.65 m/s, therefore the correct option is (A).
The average speed is calculated by the formula
Average speed= (total distance/ total time)
The total distance of the trip=9.5+3.5+15=28 m
The total time of trip=43 sec
Therefore the average speed=28/43=0.65 m/s.
Answer:
2.068 x 10^6 m / s
Explanation:
radius, r = 5.92 x 10^-11 m
mass of electron, m = 9.1 x 10^-31 kg
charge of electron, q = 1.6 x 10^-19 C
As the electron is revolving in a circular path, it experiences a centripetal force which is balanced by the electrostatic force between the electron and the nucleus.
centripetal force = 
Electrostatic force = 
where, k be the Coulombic constant, k = 9 x 10^9 Nm^2 / C^2
So, balancing both the forces we get



v = 2.068 x 10^6 m / s
Thus, the speed of the electron is give by 2.068 x 10^6 m / s.
Answer:
v = 3200 m/s
Explanation:
As we know that the frequency of the sound wave is given as

wavelength of the sound wave is given as

so now we have

so we will have

