24-15=9 m/s slower in 12 seconds. So 9/12 m/s² slower. Therefore the acceleration is -0,75 m/s²
Answer:
0.002833 sec
Explanation:
Speed of light in vacuum is 
Given distance = 850 km = 850×1000=850000 m
We have to calculate the time that light take to travel the distance 850 km
Time 
So the time taken by light to travel 850 km is 0.002833 sec
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:
7.401 * 10^(-15) N
Explanation:
30 electrons will have a charge:
30 * -1.6022 * 10^(-19) C
= - 4.806 * 10^(-18) C
The relationship between electric field and electric force is:
E = F/q
This means that force, F, is
|F| = |E|*|q|
|F| = |1540| * |-4.806 * 10^(-18)|
|F| = |-7401.24 * 10^(-18)|
|F| = 7.401 * 10^(-15) N
Potential energy is high and kinetic is equal i believe.