To convert from newtons to kg in earth gravity, simply divide by 10 (or 9.8 if being specific). 645N = ~64.5kg
Answer: 
Explanation:
Given
Mass 
Spring constant 
Compression in the spring 
When the mass leaves the spring, the elastic potential energy of spring is being converted into kinetic energy of mass i.e.

The kinetic energy of the mass is 1.102 J.
Answer:
The mirror in these telescopes will be constructed from many smaller mirrors which will work together.
Explanation:
A telescope is defined as an optical instrument that is used to observe or view the distant objects. A telescope is made up of curved lenses or mirrors or by combining both.
In the context, both the US and the Europeans are planning to make a telescope which is 30 m and 39 m respectively. This could be possible as the mirrors that are used to make these telescope will be made from a many smaller mirrors that will work together as a single large mirror having a very large aperture.
Answer:
1 = 5.4 J
2 = 0.1979 C
3 = 5
Explanation:
Energy in a capacitor, E is
E = 1/2 * C * V²
E = 1/2 * 3000*10^-6 * 60²
E = 1/2 * 3000*10^-6 * 3600
E = 1/2 * 10.8
E = 5.4 J
E = Q²/2C = 6.53 J
E * 2C = Q²
Q² = 6.53 * 2 * 3000*10^-6
Q² = 13.06 * 3000*10^-6
Q² = 0.03918
Q = √0.03918
Q = 0.1979 C
The Capacitor, C is inversely proportional to the distance of separation, D. Thus, if D is increased by 5 to be 5D, then C would be C/5. And therefore, our energy stored in the capacitor is increased by a factor of 5.