Question

6. [-19 Points] DETAILS SERPSET9 30.P.066. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER Rail guns have been suggested for launching projectiles into space without chemical rockets. A tabletop model rail gun (see figure below) consists of two long, parallel, horizontal rails l = 3.80 cm apart, bridged by a bar of mass m = 2.95 g that is free to slide without friction. The rails and bar have low electric resistance, and the current is limited to a constant I = 25.0 A by a power supply that is far to the left of the figure, so it has no magnetic effect on the bar. The figure shows the bar at rest at the midpoint of the rails at the moment the current is established. We wish to find the speed with which the bar leaves the rails after being released from the midpoint of the rails. (a) Find the magnitude of the magnetic field at a distance of 1.90 cm from a single long wire carrying a current 25.0 A T (b) For purposes of evaluating the magnetic field, model the rails as infinitely long. Using the result of part (a), find the magnetic field at the midpoint of the bar. magnitude direction Select (C) Argue that this value of the field will be the same at all positions of the bar to the right of the midpoint of the rails. At other points along the bar, the field is in the same direction as at the midpoint, but is larger in magnitude. Assume the average effective magnetic field along the bar is five times larger than the field at the midpoint. This answer has not been graded yet

Answer 1

Topriew of the figure!- I-25A Themeonetic field due to am along Current Carsyning wire is given by the formulai B= Mo I Edres B 2T. I=25A; o 21-9 cu = 2x107x 25 22632X10 Tang: parta) (9x102) Now there are two parallel wires and field due to twowire will be made plane of the paper. b

Now Tema; a - 2.8 X103 2085 mip2 B net = Bit B2 at midpon't BFB2 = 5.26X107T mode the plane of the Amp-bfast. paper g) Ax mamette field vs Baz and we move as close to the wire the magnetic field gets string of we approach very clope to wire 840; B 0 so field will be shanger in Rach side of the mid ponit due to respective wires. Bnet = 5x5 26X164 Now force on a current carrying wire moide a uniform magnetic field lo given by Fret- Bil 26.30X164x25x3.8x10-2 N = 2-490X10-3N = 2-5 X103N Anos e Force will be in the ticadirection let option is correct + yen ap the field Tocmitcom thrreghout the unifom bo turce will be Unitrom Bar 2.4 5x108 Now by 3rd eam of motion ve _u²+290 02= 220 888 125 0² 2:125 u=1-45721-46m/p Ano tive a-direction