Answer:

Explanation:
Refractive Index: It is a measure to find how fast the light travels through a medium. It is ration of the speed of light in vacuum to speed of light in the medium. Speed of light is not constant and varies depending on the density of the medium.
In vacuum the speed of light is 300000 km/s and is denoted by c. When the light beam enters any medium the speed will decrease. Here it is given that the speed in plastic is v. Thus the refractive index(n) is given as:

It is a dimensionless no.
Answer:
Time spent on the greenway road = 4.5 hours
Time spent on the 2 lane road = 1.5 hours
Explanation:
The distance of the trip is 360 miles and the initial speed of the car is 62 miles/hr and after the road became 2 lane highway the car slowed to 54 miles/hr.
Let us divide the trip into two
Greenway
speed = distance/time
speed = 62 mph
time = a
distance = speed × time
distance = 62a
2 lane highway
speed = distance/time
speed = 54 mph
time = b
distance = speed × time
distance = 54b
Total distance
62a + 54b = 360......................(i)
Total time
a + b = 6..............................(ii)
a = 6-b
insert a in equation (i)
62(6-b) + 54b = 360
372 - 62b + 54b = 360
-8b = 360-372
-8b = - 12
b = 12/8
b = 1.5
from equation (ii)
a + 1.5 = 6
a = 6 - 1.5
a = 4.5
The long structure of small intestine is accommodated in small space within our body because of extensive coiling. the small intestine is highly coiled structure and thus can easily be fixed in a small space.
Answer:
Those substances which can conduct electricity are called conductors, while those substances which don't conduct electricity are called insulators.
Resistance is the obstruction provided by the material through which the current passes,so since conductors conduct electricity and insulators don't,so the obstruction i.e resistance provided by the conductor must be less,while insulators being unable to conduct electricity,has very high resistance.
Example of conductor is copper
Example of insulator is plastic
<span> Balanced. If not so, then the car cannot move with uniform speed. The frictional force is balanced by the force exerted by the engine. </span>