As shown in the figure, Mn and PQ are two parallel metal guides placed in the vertical plane and long enough, with a distance of L = 50cm. The guide is in the uniform magnetic field with a vertical paper inward magnetic induction intensity of B = 5T. A metal bar AB with a resistance of 0.1 Ω can move left and right close to the guide. Two parallel metal plates a and C with a phase distance of D = 10cm and a length of L = 20cm are connected with the two parallel guides respectively It is known that when the metal bar AB is not moving, the small ball with mass m = 10g and charge q = - 10-3c shoots into the plate along the middle line of metal plate A and C at a certain speed V0, and can just shoot out the metal plate (G is taken as 10m / S2) (1) The velocity of the ball V0; (2) if the ball does not deflect between the metal plates, the velocity and direction of the metal bar AB; (3) if the ball can be ejected between the metal plates, what conditions should be met for the uniform velocity of the metal bar AB?

As shown in the figure, Mn and PQ are two parallel metal guides placed in the vertical plane and long enough, with a distance of L = 50cm. The guide is in the uniform magnetic field with a vertical paper inward magnetic induction intensity of B = 5T. A metal bar AB with a resistance of 0.1 Ω can move left and right close to the guide. Two parallel metal plates a and C with a phase distance of D = 10cm and a length of L = 20cm are connected with the two parallel guides respectively It is known that when the metal bar AB is not moving, the small ball with mass m = 10g and charge q = - 10-3c shoots into the plate along the middle line of metal plate A and C at a certain speed V0, and can just shoot out the metal plate (G is taken as 10m / S2) (1) The velocity of the ball V0; (2) if the ball does not deflect between the metal plates, the velocity and direction of the metal bar AB; (3) if the ball can be ejected between the metal plates, what conditions should be met for the uniform velocity of the metal bar AB?

(1) The horizontal displacement is the length of the metal plate l = 20cm, and the vertical displacement is equal to D2 = 5cm. According to the motion law of horizontal throw: & nbsp; D2 = 12gt2, & nbsp; D2 = 12g (lv0) 2, the solution is: V0 = LGD = 0.2 × 100.1m/s = 2m / S (2)