The wavelength of a sound wave is related to its frequency by the relationship:

where
f is the frequency
v is the speed of the wave

is the wavelength
The wave in our problem has wavelength of

and speed of

(this is the speed of sound in air), therefore its frequency is

And the period of the wave is equal to the reciprocal of its frequency:
To solve this problem it is necessary to apply the concepts related to Hooke's Law as well as Newton's second law.
By definition we know that Newton's second law is defined as

m = mass
a = Acceleration
By Hooke's law force is described as

Here,
k = Gravitational constant
x = Displacement
To develop this problem it is necessary to consider the two cases that give us concerning the elongation of the body.
The force to keep in balance must be preserved, so the force by the weight stipulated in Newton's second law and the force by Hooke's elongation are equal, so

So for state 1 we have that with 0.2kg there is an elongation of 9.5cm


For state 2 we have that with 1Kg there is an elongation of 12cm


We have two equations with two unknowns therefore solving for both,


In this way converting the units,


Therefore the spring constant is 313.6N/m
Answer: When you name an element, it's usually because the element is newly discovered. So by naming an element you are creating something that will last throughout history.
Explanation:
Speed = d/t
d = 200, t = 10
200/10 = 20
Solution: 20 m/s