Answer:
a) 
b) 
Explanation:
Given:
- speed of rocket initially,
- top speed of rocket after acceleration,
- time taken to get to the top speed,
- final speed of the rocket,
- time taken to get to the final speed after reaching the top speed,
Now the acceleration:
Now as a fraction of gravity:
Now, the deceleration:
Now as a fraction of gravity:
In summary, gravity is the force that creates the pressure to fuse atoms, which makes the stars shine. Eventually the temperature is high enough that the star starts fusing hydrogen into helium. When the outward pressure produced by the heating of the gas by fusion energy balances gravity, a stable star is formed.
Answer:
The US Environmental Protection Agency (EPA) sets limits for exposure to x-rays and gamma rays in part because it recognizes that this form of radiation can cause cancer.
Answer:
Nuclear fusion and gravitational contraction
Explanation:
In stars, there is an equilibrium between two forces, the force of gravity in the inward direction due to their own mass, and the radiation pressure in the upward direction as a consequence of the nuclear reaction in their core, that is known as hydrostatic equilibrium.
The radiation pressure is gotten from the nuclear reactions at the core (when lighter elements fuse into heavier elements), but if the nuclear reactions stop, hence, the radiation pressure will also do it and the force of gravity will overcome and break the equilibrium.
Both of that energy sources help to maintain a star's internal thermal pressure, since the contractions of the superficial layers will increase the density at the core.
