Speed Bar
What is the terminal speed at which the bar falls? Assume the bar remains horizontal and in contact with the r?
A 60 horizontal metal bar, 12 long, is free to slide up and down between two tall, vertical metal rods. A 5.0×10−2 magnetic field is directed perpendicular to the plane of the rods. The bar is raised to near the top of the rods, and a 1.0 resistor is connected across the two rods at the top. Then the bar is dropped.
F = mg = ILB ==> I = mg/(LB)
Energy = Fv = mgv = I^2R ==>
v = I^2R/(mg) = (mg/(LB))^2R/mg = mgR/(LB)^2
B = 0.05 T, g = 9.81 m/s^2
Since you didn't provide any units, I can only guess at the rest.
m = 60 g (0.06 kg), L = 12 cm (0.12 m), R = 1 ohm
v = 0.06*9.81*1/(0.12*0.05)^2 = 16350 m/s
 |
 Shimano Bar End Shifters Compatible with RD 7700 9 Speed and RD 7400 8 Speed $66.00 (6 Bids) Time Remaining: 2h 4m |
 Campagnolo 2007 Veloce 10x 3 speed Ergopower flat bar control levers NIB $140.00 (1 Bid) Time Remaining: 3h 3m |
 Full Speed Ahead Vision Time Trail Bars $49.00 Time Remaining: 4h 13m |
 Campagnolo 11 Speed Bar End Shifters $86.00 (8 Bids) Time Remaining: 4h 17m |
 TRACKFIXIESINGLE SPEED BIKE HANDLEBAR BAR GRIPS GREEN $0.99 Time Remaining: 7h 4m Buy It Now for only: $0.99 |
 shimano 8 speed 105 tiagra ultegra duraace bar end shifters index or friction NR $23.00 (4 Bids) Time Remaining: 18h 53m |
 Shimano Dura Ace 9 Speed Bar End Shifters $51.01 (7 Bids) Time Remaining: 22h 34m |
 Shimano SL BS64 Ultegra Left Bar End Shifter 2 3 x 8 Speed $20.00 Time Remaining: 1d 11h 19m |
 NEW CAMPAGNOLO SL12 TT CARBON BAR END 11 SPEED SHIFTER SET WITH CABLES CAMPY $10.50 (5 Bids) Time Remaining: 1d 15h 18m |
 shimano dura ace 10 speed bar end shifters for time trial tt or triathlon $12.50 (7 Bids) Time Remaining: 1d 21h 26m |
 Campagnolo 8 Speed Bar End Shifters Time Trial Triathlon NEW NOS $49.99 Time Remaining: 1d 22h 55m |
 Campagnolo Record 10 speed bar end Time Trial TT Shifters $16.50 (8 Bids) Time Remaining: 2d 2h 2m |
 Bike Bicycle Fixie Single Speed BMX Threadless Handlebar Handle Bar Stem Gold $26.99 Time Remaining: 2d 3h 40m Buy It Now for only: $26.99 |
 Origin 8 Bike Single Speed Fixie Bull Horn Handle Bar Bullhorn Handlebars Silver $25.99 Time Remaining: 2d 3h 42m Buy It Now for only: $25.99 |
 FIXIE FIXED GEAR SINGLE SPEED TRACK HANDLEBARBARRETRO $32.87 Time Remaining: 2d 4h 1m Buy It Now for only: $32.87 |
 Bike Bicycle Fixie Single Speed BMX Threadless Handlebar Bar Stem Purple 222 $26.99 Time Remaining: 2d 4h 24m Buy It Now for only: $26.99 |
 SHIMANO ULTEGRA SL R770 2 Speed Left Mtb Road Bike Shifter Flat Bar NEW $49.97 Time Remaining: 2d 4h 46m |
 Road Bike Bicycle Fixie Single Speed Threadless Alloy Bar Stem 254 50mm Blue $26.99 Time Remaining: 2d 10h 10m Buy It Now for only: $26.99 |
 Bike Bicycle Single Speed Fixie 50mm 1 1 8 Threadless Alloy Bar Stem 254 Orange $26.99 Time Remaining: 2d 10h 21m Buy It Now for only: $26.99 |
 Bike Bicycle Single Speed Fixed 50mm 1 1 8 Threadless Alloy Bar Stem 254 Green $26.99 Time Remaining: 2d 10h 24m Buy It Now for only: $26.99 |
 Shimano SL BS79 Dura Ace 10 Speed SIS Index Bar End Shifter Triathlon TT Bikes $96.75 Time Remaining: 2d 20h 43m Buy It Now for only: $96.75 |
 New Microshift BS A10 10 speed bar end shifters $20.00 Time Remaining: 3d 1m |
 SRAM Bar End Shifter Set 10 Speed $19.99 (1 Bid) Time Remaining: 3d 6h 10m |
 Token Blue FIXIETRACKSINGLE SPEED BIKE HANDLEBAR BAR with GRIPS fixed gear $25.99 Time Remaining: 3d 8h 42m Buy It Now for only: $35.99 |
 NEW SPEED PARK Marble Pattern Plastic Bar End + Plug $12.18 Time Remaining: 3d 10h 25m Buy It Now for only: $12.18 |
 Bike Bicycle Single Speed Fixie 254mm 318mm Threadless Handlebar Bar Stem Blue $25.99 Time Remaining: 3d 10h 49m Buy It Now for only: $25.99 |
 NEW Bike Bicycle Single Speed Fixie 254 318 Threadless Handlebar Bar Stem Red $25.99 Time Remaining: 3d 10h 52m Buy It Now for only: $25.99 |
 Bike Bicycle Fixie Single Speed 254 318 Threadless Handlebar Bar Stem Green $25.99 Time Remaining: 3d 10h 55m Buy It Now for only: $25.99 |
 Bike Bicycle Fixie Single Speed 254 318 Threadless Handlebar Bar Stem Yellow $25.99 Time Remaining: 3d 10h 57m Buy It Now for only: $25.99 |
 Vintage Schwinn Bike Bicycle Parts Varsity 10 Speed Handle Bars Handlebars $15.00 Time Remaining: 3d 16h 57m Buy It Now for only: $15.00 |
 SRAM TT 10 Speed bar end shifters triathlon $50.00 (6 Bids) Time Remaining: 3d 23h 42m |
 Shimano Dura Ace 10 Speed SIS Index Bar End Shifter Triathlon Time Trial Bikes $109.00 Time Remaining: 4d 3h 33m Buy It Now for only: $109.00 |
 ZIPP SL Speed Weaponry Carbon Handle Bar 42cm out out 318mm Clamp $0.99 (1 Bid) Time Remaining: 4d 5h 31m |
 Shimano Dura Ace SL 7700 Dura Ace 9 speed bar end shifters with adjuster $94.99 Time Remaining: 4d 9h 3m Buy It Now for only: $94.99 |
 Dura Ace Bar End Shift Levers SL BS79 10 speed triathlon shifters time trial VGC $88.95 Time Remaining: 4d 10h 34m Buy It Now for only: $88.95 |
 NEW Dura Ace Bar End Shift Levers SL BS79 10 speed triathlon shifters time trial $127.50 Time Remaining: 4d 11h Buy It Now for only: $127.50 |
 NEW Bike Bicycle Single Speed Fixie Handlebar Handle Bar Grip Grips Blue Black $10.79 Time Remaining: 4d 11h 55m Buy It Now for only: $10.79 |
 Bike Bicycle Single Speed Fixie Handlebar Handle Bar Grip Grips Purple Black $10.79 Time Remaining: 4d 11h 57m Buy It Now for only: $10.79 |
 NEW Bike Bicycle Single Speed Fixie Handlebar Handle Bar Grip Grips Red Black $10.79 Time Remaining: 4d 11h 58m Buy It Now for only: $10.79 |
 Bike Bicycle Single Speed Fixie Handlebar Handle Bar Grip Grips Silver Black $10.79 Time Remaining: 4d 11h 59m Buy It Now for only: $10.79 |
 GIANT Road Bike Fixed Gear Single Speed Handlebar Tape Bar Wrap White Black $11.99 Time Remaining: 4d 13h 50m Buy It Now for only: $11.99 |
 GIANT Road Bike Fixed Gear Single Speed Handlebar Tape Bar Wrap White $14.99 Time Remaining: 4d 13h 50m Buy It Now for only: $14.99 |
 GIANT Road Bike Fixed Gear Single Speed Handlebar Tape Bar Wrap Red $14.99 Time Remaining: 4d 13h 50m Buy It Now for only: $14.99 |
 GIANT Road Bike Fixed Gear Single Speed Handlebar Tape Bar Wrap Blue $14.99 Time Remaining: 4d 13h 50m Buy It Now for only: $14.99 |
 GIANT MOMENTUM Road Bike Fixed Gear Single Speed Handlebar Tape Bar Wrap Orange $14.99 Time Remaining: 4d 13h 50m Buy It Now for only: $14.99 |
 GIANT Road Bike Fixed Gear Single Speed Handlebar Tape Bar Wrap Golden $14.99 Time Remaining: 4d 13h 50m Buy It Now for only: $14.99 |
 GIANT MOMENTUM Road Bike Fixed Gear Single Speed Handlebar Tape Bar Wrap Leopard $14.99 Time Remaining: 4d 13h 50m Buy It Now for only: $14.99 |
 GIANT Road Bike Fixed Gear Single Speed Handlebar Tape Bar Wrap Red Black $11.99 Time Remaining: 4d 13h 50m Buy It Now for only: $11.99 |
 GIANT MOMENTUM Road Bike Fixed Gear Single Speed Handlebar Tape Bar Wrap White $14.99 Time Remaining: 4d 13h 50m Buy It Now for only: $14.99 |
 GIANT Road Bike Fixed Gear Single Speed Handlebar Tape Bar Wrap Pink $14.99 Time Remaining: 4d 13h 50m Buy It Now for only: $14.99 |
 GIANT Road Bike Fixed Gear Single Speed Handlebar Tape Bar Wrap Yellow $14.99 Time Remaining: 4d 13h 56m Buy It Now for only: $14.99 |
 GIANT Road Bike Fixed Gear Single Speed Handlebar Tape Bar Wrap Yellow Black $11.99 Time Remaining: 4d 13h 56m Buy It Now for only: $11.99 |
 Sram R2C TT shifters 1090 Time Trial Bar End Shift Levers NEW 10 speed $319.99 Time Remaining: 4d 22h 44m Buy It Now for only: $319.99 |
 2010 Sram FLAT BAR doubletap shifter flatbar hybrid Bicycle 3x9 speed NEW $89.99 Time Remaining: 4d 22h 44m Buy It Now for only: $89.99 |
 Sram TT900 Bar End Shifters Carbon 2x10 speed New 138g Time Trial Bicycle TT $166.99 Time Remaining: 4d 22h 44m Buy It Now for only: $166.99 |
 Vintage Maruishi 10 Speed Handle BarsVintage Bicycle Parts Bicycle Handlebars $10.00 Time Remaining: 5d 25m |
 Fixie Track Single Speed Bike Alloy Drop Bar Pistabar 318 Handlebar 40cm Pink $49.99 Time Remaining: 5d 1h 55m Buy It Now for only: $49.99 |
 Shimano SL BS77 Dura Ace Bar End Shifters 9 Speed $0.01 (1 Bid) Time Remaining: 5d 3h 15m |
 Shimano Dura Ace BS77 Bar End Shifters 9spd Speed Time Trial Triathlon Levers $50.99 (2 Bids) Time Remaining: 5d 5h 58m |
 Shimano SL BS64 Bar End Shifters 8spd Speed Road Bike Cyclocross $34.99 Time Remaining: 5d 6h 27m Buy It Now for only: $49.99 |
 Bike Bicycle Fixie Single Speed Short Alloy BMX Handlebar Handle Bar Black 222 $28.79 Time Remaining: 5d 7h 41m Buy It Now for only: $28.79 |
 Bike Bicycle Fixie Single Speed Short Alloy BMX Handlebar Handle Bar White 222 $28.79 Time Remaining: 5d 7h 43m Buy It Now for only: $28.79 |
 Bike Bicycle Fixie Single Speed Short Alloy BMX Handlebar Handle Bar Blue 222 $28.79 Time Remaining: 5d 7h 45m Buy It Now for only: $28.79 |
 Bike Bicycle Fixie Single Speed Short Alloy BMX Handlebar Handle Bar Green 222 $28.79 Time Remaining: 5d 7h 48m Buy It Now for only: $28.79 |
 Bike Bicycle Fixie Single Speed Short Alloy BMX Handlebar Handle Bar Orange 222 $28.79 Time Remaining: 5d 7h 49m Buy It Now for only: $28.79 |
 Bike Bicycle Fixie Single Speed Short Alloy BMX Handlebar Handle Bar Purple 222 $28.79 Time Remaining: 5d 7h 50m Buy It Now for only: $28.79 |
 Bike Bicycle Fixie Single Speed Short Alloy BMX Handlebar Handle Bar Red 222 $28.79 Time Remaining: 5d 7h 52m Buy It Now for only: $28.79 |
 Bike Bicycle Fixie Single Speed Short Alloy BMX Handlebar Handle Bar Silver 222 $28.79 Time Remaining: 5d 7h 53m Buy It Now for only: $28.79 |
 Fixie Track Single Speed Bike Alloy Drop Bar Pistabar 318 Handlebar 40cm Pink $47.99 Time Remaining: 5d 8h 2m |
 Fixie Track Single Speed Bike Alloy Drop Bar Pistabar 254 Handlebar 40cm Gold $47.99 Time Remaining: 5d 8h 8m |
 SRAM 2011 TT500 Time Trial 2x10 Speed Bar End Shifters $131.95 Time Remaining: 5d 9h 10m Buy It Now for only: $131.95 |
 Fixie Track Single Speed Bike Alloy Drop Bar Pistabar 254 Handlebar 40cm Silver $47.99 Time Remaining: 5d 9h 30m |
 Fixie Track Single Speed Bike Alloy Drop Bar Pistabar 254 Handlebar 40cm White $47.99 Time Remaining: 5d 10h 28m |
 NEW CAMPAGNOLO SL12 TT CARBON BAR END 11 SPEED SHIFTER SET WITH CABLES CAMPY $365.49 Time Remaining: 5d 18h 25m Buy It Now for only: $365.49 |
 Shimano SL BS77 Dura Ace Double Triple Bar End Shifter 9 Speed RIGHT ONLY $1.82 (3 Bids) Time Remaining: 5d 23h 52m |
 NEW Shimano FD R770 Braze on 10 Speed Road Bike Flat Bar Front Derailleur $19.99 Time Remaining: 6d 2h 59m Buy It Now for only: $19.99 |