(20 1 1? As shown in the figure, a positively charged ball with a mass of m is sleeved on a vertical insulating rod and can slide vertically along the rod to uniformly enhance the magnetic induction i

(20 1 1? As shown in the figure, a positively charged ball with a mass of m is sleeved on a vertical insulating rod and can slide vertically along the rod to uniformly enhance the magnetic induction intensity of the magnetic field. The ball is subjected to gravity, Lorentz force, supporting force and upward sliding friction. As the speed increases, the Lorentz force increases, the supporting force increases, the sliding friction increases, the resultant force decreases, the object accelerates and the acceleration decreases. When the acceleration drops to zero, the speed is the maximum;

When the velocity is zero, the Lorentz force is zero, so the object is only subjected to gravity, and the acceleration is the largest, g;

The object finally moves in a straight line at the maximum speed, including:

Horizontal direction: N=qvB

Vertical direction: mg-f=0

Where: f=μN

Solution: v=mgμBq

So the answer is: g, mg μ bq.