Answer:
1)
from the positive x-axis.
2) 
Explanation:
Given:
speed of rowing in still water, 
1)
speed of water stream, 
we know that the direction of resultant of the two vectors is given by:

where:
the angle of resultant vector from the positive x-axis.
angle between the given vectors
When the rower wants to reach at the opposite end then:

so,




from the positive x-axis.
2)
Now the resultant velocity of rowing in the stream:



Therefore time taken to cross a 4 miles wide river:



To solve this problem we apply the concepts related to the electric torque generated by the electromagnetic field. Mathematically this Torque can be written under the following relation

Here,
N = Number of Turns
I = Current
A = Area
B = Magnetic Field
The maximum torque will be reached when the angle is 90 degrees, then we will have the following relation,

Magnetic Field is given at function of the number of loops, permeability constant at free space at the perimeter, then



Replacing at the first equation we have,


Answer:
Por ela ter batido na trave, não tem como voltar 2x mais forte, por que toda ação correspondente a uma reação de igual intensidade, mas que atua no sentido oposto
Explanation:
Ford was the first person to receive this patent.
Answer:
The focal length of eye piece is 6.52 cm.
Explanation:
Given that,
Angular Magnification of the microscope M = -46
the distance between the lens in microscope L= 16 cm
The focal length of objective f₀ = 1.5 cm
Normal near point N = 25 cm
Have to find focal length of eye piece f ₙ =?
The angular magnification is given by
M ≈ - (L-fₙ)N/f₀fₙ
Rearranging for fₙ
fₙ =L(1 - Mf₀/N)⁺¹
=18/2.76
fₙ = 6.52 cm
The focal length of eye piece is 6.52 cm.