30 + 6 = 36
36/12 = 3
So, it would take it 3 hours to go 12 kms downstream.
Note that we added 30 and 6 because it was going downstream. If it was going upstream, then we would have had to subtract.
Yes they do. So if you need to add or subtract a pair, then you have to first change one or the other so that they both have the same power of 10.
Answer:
The loss of trees and other vegetation can cause climate change, desertification, soil erosion, fewer crops, flooding, increased greenhouse gases in the atmosphere, and a host of problems for indigenous people.
The magnitude of the average emf induced in the loop is given by (we ignore the signs since we are interested only in the magnitude)
where
is the variation of magnetic flux through the area enclosed by the loop, and
is the time interval.
The magnetic flux is given by
where B is the intensity of the magnetic field, A is the area enclosed by the loop and
is the angle between the perpendicular to the area and the magnetic field. In our problem, this angle is zero because the loop is perpendicular to the magnetic field, so the cosine is 1. The area of the loop is fixed, and it is
where
is the radius of the loop. The only element which is variable in the formula is B, which changes from 0.069 T to -0.044 T (opposite direction). So we can rewrite the flux variation as
where
By using
, we can find the magnitude of the emf induced: