Note: I'm not sure what do you mean by "weight 0.05 kg/L". I assume it means the mass per unit of length, so it should be "0.05 kg/m".
Solution:
The fundamental frequency in a standing wave is given by

where L is the length of the string, T the tension and m its mass. If we plug the data of the problem into the equation, we find

The wavelength of the standing wave is instead twice the length of the string:

So the speed of the wave is

And the time the pulse takes to reach the shop is the distance covered divided by the speed:
A wall uses diffuse reflection while a mirror uses specular reflection. For example, when parallel light rays enter a mirror, they remain parallel when exiting the mirror, allowing you to see a reflection of the light rays. On the contrary, when incident light rays enter a wall which is painted, the rays scatter, not allowing you to see anything but a painted wall.
Very specific alignment of the Sun, Earth, and Moon. If the Moon is lined up precisely with the Sun from the Earth's point of view, the Moon will block Sunlight from reaching the Earth, causing a solar eclipse.
Answer:
The right solution will be the "2v".
Explanation:
For something like an object underneath pure rolling the speed at any point is calculated by:
⇒ 
Although the angular velocity was indeed closely linked to either the transnational velocity throughout particular instance of pure rolling as:
⇒ 
Significant meaning is obtained, as speeds are in the same direction. Therefore the speed of rotation becomes supplied by:
⇒ 
On substituting the estimated values, we get
⇒ 
⇒ 
So that the velocity will be:
⇒ 
⇒ 
As we know that spring force is given as

here we know that
F = 4 N
x = 2 cm = 0.02 m
now from the above equation we will have


so the elastic constant of the spring will be 200 N/m