Awheel of mass m and radius r rolls on a level surface without slipping. if the angular velocity of the wheel about its center is ? , what is its linear momentum relative to the surface?

The most important thing you should remember in order to get how is its linear momentum relative to the surface is that the point on the circumference is moving at w rad/second. 
Therefore, here is the solving formulae:
if  you can easily get  linear momentum p :
 
I'm sure that helps.

We can infer that star y is closer but other factors must be considered include the heat of the star, the mass, and the brightness of the star. even though star x seems dimmer it may just be less bright or contains less heat.