Answer:
a) I = 13.77 A
b) 0 ° or to the East
Explanation:
Part a
The magnetic field by properties would be 0 at the radius on this case r =8.1 cm.Analyzing the situation the wirde would produce a magnetic field equals in magnitude to the magnetic field on Earth by with the inverse direction.
The formula for the magnetic field due to a wire with current is:

In order to have a value of 0 for the magnetic field at the radius then we need to have this balance
B (r=8.1) = B (Earth)
Replacing:
Solving from I, from the last equation we got:

= 13.77 A
Part b
We can use the right hand rule for this case.
The magnetic field of the wire would point to the South, because the magnetic field of the earth given points to the North. Based on this the current need's to flow from West to East in order to create a magnetic field pointing to the south, because the current would be perpendicular to the magnetic field created.
By definition, speed is the integral of acceleration with respect to time.
We have then:

As the acceleration is constant, then integrating we have:

Where,
vo: constant of integration that corresponds to the initial velocity
We observe then that the speed varies linearly when the acceleration is constant
.
Therefore, for constant acceleration, the velocity is changing.
Answer:
an object with a constant acceleration always have:
A. changing velocity
Answer:
Chinese app which is number
Explanation:
Answer: The correct answer is vacuum.
Explanation:
Sound wave is a longitudinal wave in which the particles vibrate parallel to the direction of the motion of the wave. Sound wave consists of compression and rarefaction.
It needs a medium to travel. It can travel in solid, liquid and gas. It cannot travel in vacuum.
Denser the medium, more will be the speed of the wave.
Solid is more denser in comparison to liquid.
The speed of the sound in the solid medium is more in comparison to the liquid. The speed of the sound in liquid is more than the speed in the gas.
Therefore, vacuum is least effective medium for traveling sound waves.