I think it’s 5.0 X 10 8Hz
Answer: Friction stops things from sliding apart. If there was no friction everything would slide to the lowest point. With no friction the only possible movement would be falling to a lower point under gravity.
Explanation: In a frictionless world, more objects would be sliding about, clothes and shoes would be difficult to keep on and it would be very difficult for people or cars to get moving or change direction. Students should be encouraged to consider how dependant their world is on the beneficial action of friction. Humans and other objects will become weightless without gravity. If we have no gravity force, the atmosphere would disappear into space, the moon would collide with the earth, the earth would stop rotating, we would all feel weightless, the earth would collide with the sun, and as a consequence.
Answer:
589.3 nm
Explanation:
The wavelength of a sodium light is 5893 A.
We need to find the wavelength in nm.
Also, 
So, the wavelength of sodium light is 589.3 nm.
The frictional force is always act in opposite direction of motion. if wheels is moving in +x axis or right then the f force is act in -x or left
The concepts used to solve this problem are sound power, area of ear drum, and inverse square law. First find the intensity 
using inverse square law for different distances. Then find the area of the ear drum using the diameter and finally find the energy transferred to each ear drum in one second. Intensity is inversely proportional to the square of the distance from the source:
Here,
r = Distance from the source,
Now the expression for the Area of ear drum is
The expression for Sound power is
Replacing,
Therefore the energy reached per second is 
