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Answer:
The strength of the magnetic field that the line produces is
.
Explanation:
From Biot-Savart law, the equation to determine the strength of the magnetic field for any straight wire can be deduced:
(1)
Where
is the permiability constant, I is the current and r is the distance from the wire.
Notice that it is necessary to express the current, I, from kiloampere to ampere.
⇒ 
Finally, equation 1 can be used:
Hence, the strength of the magnetic field that the line produces is
.
Answer:

Explanation:
= Angular speed
= Distance of Mary = 11.5 ft
= Distance of Alex = 6 ft
Ratio of centripetal acceleration is given by

Mary's centripetal acceleration is 1.92 times the centripetal acceleration of Alex
When the object is moving in the elliptical orbit, it means that the direction of its acceleration should be towards the two foci (plural of focus) of the ellipse to keep the elliptical motion. As force according to the Newton's second law: F = ma, the net force must be in the direction of the acceleration. As far as the magnitude of net force is concerned, you can use Newton's gravitational law to find its magnitude.