Current location - Plastic Surgery and Aesthetics Network - Plastic surgery and beauty - Minhang district pingmian metal plastic service department
Minhang district pingmian metal plastic service department
(1) When the rod falls 13, the speed is maximum, that is, the resultant force is zero, so there are:

mg= 13qE

Solution: q=3mgE

(2) Based on the kinetic energy theorem, the linear change of electric field force with displacement is considered:

mgl3? 0+qE/32? l3= 12mv2m

Replace vm=gl3 with q = 3mge.

(3) When the speed of the rod drops to zero, the falling distance is h, which is obtained from the kinetic energy theorem:

mgh? 12qE? hl? h=0

De: h = 2mglqe

From Newton's second law: qlhE? Mg = mA

Bring h into the above formula: a = g.

Answer: (1) The charge of the thin rod is 3mgE.

(2) The maximum speed of rod dropping is gl3;;

(3) At this time, the acceleration of the rod is g..