Question

A 60 g horizontal metal bar, 12 cm long, is free to slide up and down between two tall, vertical metal rods that are 12 cm apart. A 0.080 T magnetic field is directed perpendicular to the plane of the rods. The bar is raised to near the top of the rods, and a 1.5 Ω resistor is connected across the two rods at the top. Then the bar is dropped. What is the terminal speed at which the bar falls? Assume the bar remains horizontal and in contact with the rods at all times.

Answer 1

/ solution :- Given that mats, m = 60g 00 60 x 10 length, L= 12 cm 07 0.12 m - 3 m = kg R= 1.5 2 magnetic field, B= 0.080 T Resistance, The terminal speed will be attained when the net force on the rod is Zero . The free body diagram of the rod Fm is, mg ILB ng I = ng LB 2 Foo ng I ²R 3 SO Energy, IZR mg value of I from equation 2 is fut in equation ③ 2 ve get,

(mg) ² R (LB2 mg or mg R L² B² So putting all known values in and to find terminal above equation velocity so that, box to 3 x 9.80x 1.5 (0.12,2 x (0.0802 882 x 10-3 0.0 144 X 64 x 10 4 882 x 10-3 0.9216 x so o 4 m/s 1 le 9 57.031 x Lo ma OY 9570.3 m/s which the The terminal spoed at bar falls is 9570.3 m/s