Regions in the milky way where density waves have caused gas clouds to crash into each other are called clumps.Clumps are molecular clouds (interstellar clouds) with higher density,where lots of dust and gs cores resides. These clouds are the beginning of stars.
Http://earthguide.ucsd.edu/virtualmuseum/virtualmuseum/OriginofGulfStream.shtml this website might help u find ur answer
Gravitational force depends on inverse square law. That is, gravitational force is inversely proportional to square of distance between asteroids.
As distance between them decreases, gravitational force increases. Hence A is correct.
Bodies in space traveled in circles.
The planets revolved around the Earth.
Answer:
The ratio is 9.95
Solution:
As per the question:
Amplitude, 
Wavelength, 
Now,
To calculate the ratio of the maximum particle speed to the speed of the wave:
For the maximum speed of the particle:

where
= angular speed of the particle
Thus

Now,
The wave speed is given by:

Now,
The ratio is given by:

