9) .Thisrecoilistheresultof actionreactionforcepairs. .ConsistentwithNewton'sthirdlawofmo tion, A. . B. . C. .

B. Smaller than the acceleration of the bullet.

Explanation:

According to the law of  conservation of momentum; the total momentum of the gun and bullet after firing is equal to the total momentum of the gun and bullet before firing.

However, the mass of gun is much larger than that of the bullet hence it follows that the velocity and acceleration during the recoil of the rifle is much smaller in comparison to the velocity and acceleration of the of bullet.

So; the acceleration of the rifle is given by the force exerted on the rife by the bullet divided by the mass of the rifle. Given that the mass of the rifle is much greater than the mass of the bullet, the acceleration of the rifle is much less than that of the bullet.

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it