Gas. I know this because first you will need to do the equator so I will say gas
Answer:
9 cm.
Explanation:
The energy used for stretch the spring from
to
will be ,
The energy used for stretch the spring from
to
will be ,
using the energy of spring formula ,we find that


Dividing both the equation will get,

Therefore, the natural length of the spring is, 9 cm.
Answer:
The importance of international bureau of weights and measures are;
1. to bring unification of measurement system.
2. to establish and preserve fundamental international prototypes.
3. to verify national standards, etc.
Here we can use the work energy theorem

here we know that

as it come to rest finally



now work done by friction force will be given as


Work done by spring force is given as



so now plug in all data above


so above is the friction coefficient
Answer:
B. the light will reach the front of the rocket at the same instant that it reaches the back of the rocket.
Explanation:
To an observer at rest in the rocket who can't see either sides of the rocket, the speed of the light is constant which means the distance to the front or the back is same and would appear to reach the rocket at the same time.
Although from the point of view of the person on the earth, the front of the rocket is travelling in opposite direction of the light while the back of the rocket is moving closer to the light. This means that the distance travelled by the light going forward will be longer going backwards. And since the speed of light is constant in both directions, the light will reach the back of the rocket before it reaches the front for the observer on the earth.