A vertically oriented square loop of copper wire falls from a region where the field!B is horizontal,uniform, and perpendicular to the plane of the loop, into a region where the field is zero. The loop is released from rest and is initially entirely within the magnetic-field region, where the magnitude of thefield is 0.300 T. Let the side length of the loop be s = 20.0 cm and the diameter of the wire be d =2.00 mm. The resistivity of copper is 1.72 " 10-8 #m and its density is 8960 kg/m3. The loop reaches its terminal speed while the upper side of the square is still in the magnetic-field region. a) Find an expression for the terminal speed in terms of the given variables, such as the resistivity of copper (%), the density of copper (%m), s, d, B, and the acceleration due to gravity, g. !Do not plug in numerical values for any quantities yet. b) Evaluate the terminal speed in m/s. c) Show that your expression for the terminal speed gives the correct units for a velocity. !To do this you will need to substitute for each unit that appears, such as Ohms, its equivalent in terms of simpler units such as kg, m, s, and C. 問a 我只知關鍵是自由落體下端進入磁場時,會有磁力抵抗讓速度變慢 上端也進入磁場後就回到只有重力狀態 問題是這題求終端和它給我的a條件讓我不是很確定我的方法感覺好像怪怪手 有哪位大大可以幫忙一下嗎? 感謝不盡^^ --

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