Question

1. You are free-floating in space and feel no acceleration. You notice a clock sitting on a planet surface. What do you notice about the clock compared to your watch? Would you expect the same thing for a clock in an accelerating spaceship and why?
2. Spiral galaxies tend to be bluer in colour than elliptical galaxies. What does this tell us about the make up of spiral galaxies?
3. Say we live in another galaxy. We observe the galaxy's globular clusters and they appear to be uniformly spread out in all directions. What would this tell us about where we are in the galaxy and why?

Answer 1

1) if we are floating in space we will feel no gravity and thus watch will stop ticking while any watch on planet will continue to tick depending upon the value of gravity.

If we are in accelerated spaceship then condition will not be same since now we are experiencing acceleration.

2) Spiral galaxies are bluer in colour compared to elliptical galaxies and this shows that spiral galaxies are made up of young hot stars while elliptical one is comparatively older and thus cooler.

Blue colour indicate the hotness of object.

3) Globular cluster contain oldest stars of galaxy and are found surrounding the spiral galaxies. These are mostly situated around the halo of galaxy so we can conclude that we are in the galactic halo region.