Answer:
a

b

Explanation:
From the question we are told that
The speed of the spaceship is 
Here c is the speed of light with value 
The length is 
The distance of the star for earth is 
The speed is 
Generally the from the length contraction equation we have that
![l = l_o \sqrt{1 -[\frac{v}{c } ]}](https://tex.z-dn.net/?f=l%20%20%3D%20%20l_o%20%20%5Csqrt%7B1%20-%5B%5Cfrac%7Bv%7D%7Bc%20%7D%20%5D%7D)
Now the when at rest the length is 
So



Considering b
Applying above equation
![l =l_o \sqrt{1 - [\frac{v}{c } ]}](https://tex.z-dn.net/?f=l%20%20%3Dl_o%20%5Csqrt%7B1%20-%20%20%5B%5Cfrac%7Bv%7D%7Bc%20%7D%20%5D%7D)
Here 
So



The answer is divergent boundaries.
I hope this helps you!
Definitely D. The brakes on a bike rub against the wheel. Not sure about the others.
Answer:
The order of increasing energy is as follows
"microwave < infrared < visible < ultraviolet"
Option (A) is correct.
Explanation:
Given:
Arrange the following spectral regions in order of increasing energy: infrared, microwave, ultraviolet, visible.
From the formula of energy in terms of frequency.

Where
planck constant,
frequency of light.
From above formula we can conclude that higher frequency means higher energy.
In our case ultraviolet has higher frequency and microwave has lower frequency.
So ultraviolet has higher energy and microwave has lower energy.
microwave < infrared < visible < ultraviolet
Therefore, the order of increasing energy is as follows
"microwave < infrared < visible < ultraviolet"
Answer:
u = - 38.85 m/s^-1
Explanation:
given data:
acceleration = 2.10*10^4 m/s^2
time = 1.85*10^{-3} s
final velocity = 0 m/s
from equation of motion we have following relation
v = u +at
0 = u + 2.10*10^4 *1.85*10^{-3}
0 = u + (21 *1.85)
0 = u + 38.85
u = - 38.85 m/s^-1
negative sign indicate that the ball bounce in opposite directon