No light does not need medium to travel.Its an electromagnetic(EM) wave.All EM waves travel independent of medium. In contrast mechanical waves need a medium,sound waves,shock waves are mechanical and they need medium to transfer energy or travel.
Answer: C. -1.16 meters/second2
Explanation:
A= v/t (velocity/time)
in this case: v=7 and t=6
So, A= 7/6
A=1.16
The graph is decreasing so accelleration would be negative
A= <u>-1.16 meters/second2</u>
<u>Option C!</u> ; )
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Answer:

Explanation:
We have given number of turns N = 560
Inductance L = 8.9 mH
Current through the coil = 7 mA
Inductance of the coil is given as 
Where N is number of turns I is current and
is flux
So 
As we know that gravitational potential energy is given by

here we have
m = mass = 120 kg

h = height = 8.2 m
now from above formula


so above is the gravitational potential energy of the couch