Question



求解🙇
課本給的答案是(a)1.91cm/s(b)left

41 M In Fig. 28.31, a metal wire of mass m = 24.1 mg can slide
with negligible friction on two horizontal parallel rails separated
by distance d=2.56 cm. The track lies in a vertical uniform mag-
netic field of magnitude 56.3 mT. At time t = 0, device G is con-
nected to the rails, producing a constant current i = 35.0 mA in
the wire and rails (even as the wire moves). At t = 61.1 ms, what
are the wire's (a) speed and (b) direction of motion (left or right)?
d
m
B
FIGURE 28.31 Problem 41.