Answer:

Explanation:
The refractive index of a medium is a measure to know how much the speed of light within the medium is reduced. It can be calculated with the next equation:
(1)
Where:


The speed of light in the vacuum is approximately 300,000 km/s. In order to work with the same units let's do the proper conversion with the velocity of the medium:

Finally, replacing the data in (1):

The simplest way to do this is to set up equivalent fractions, like this-

=

Solve for x by using cross multiplication.
40*2.2= 88
1*x=88
x=88
Therefore, the boy weighs 88lbs.
Answer:
Part a)
acceleration = -0.042 m/s/s
Part b)
initial speed = 14.17 m/s
final speed = 5.77 m/s
Explanation:
Part a)
Let the initial velocity of the motorcycle is

now at the end of 80 s let the speed is

after another 120 s let the speed will be

now we know that



also we know that

also we have


now we can say

also we know



Part b)
now we have



so the starting velocity of the trip is

now speed after t = 200 s is given as



Answer: B)To the left of the charges.
Explanation: between the charges the electric field will not cancel but will be added since electric field lines from both charges point in the same direction. To the right of the charge the -4q will take over as it’s strength overcomes the strength of the +q charge. At this point the magnitude of +q will never reach a magnitude strong enough to cancel the -4q. To the left, it is further away from -4q and is closer to +q and electric field lines point in different direction
Hydroelectricity is the best answer.
This is an article by the EIA, but the pie graph is the most helpful: https://www.eia.gov/energyexplained/?page=us_energy_home