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Unformatted text preview: s ee, the frequenc y drops as the energy (and s peed) inc reas es ; the partic les ' motion
falls out of phas e with the puls ating voltage, res tric ting the c y c lotron's ability to ac c elerate the
partic les further Rail Gun
A Rail Gun us es elec tromagnetic forc es to ac c elerate a projec tile to very high veloc ities . The bas ic
mec hanis m of ac c eleration is relatively s imple and c an be illus trated in the following ex ample. A metal rod
of mas s
and elec tric al res is tanc e
res ts on parallel horiz ontal rails (that have negligible elec tric
res is tanc e), whic h are a dis tanc e apart. The rails are als o c onnec ted to a voltage s ourc e , s o a c urrent loop is formed.
The rod begins to move if the ex ternally applied
vertic al magnetic field in whic h the rod is loc ated
reac hes the value . As s ume that the rod has a
s lightly flattened bottom s o that it s lides ins tead
of rolling. Us e for the magnitude of the
ac c eleration due to gravity . Par t A
Find , the c oeffic ient of s tatic fric tion between the rod and the rails . Ex pre ss the coe fficie nt of sta tic friction in te rm s of va ria ble s give n in the introduction. Hin t 1. How to approach this problem
The rod will begin to move when the forc e of fric tion is equal to the forc e due to the magnetic
field. Hin t 2. F orce due to the magnetic field
W hat is , the magnitude of the forc e on the rod due to the magnetic field in this problem? Give your a nsw e r in te rm s of va ria ble s give n in the introduction. session.master ing physics.com/myct/assig nmentPr intView?assig nmentID= 2252604 16/19 24 03 2013 HW- 5 Hin t 1. F ormula for the force on the rod
The forc e on the rod is . Hin t 2. F inding the current through the rod
W hat is , the c urrent through the rod? Rec all that . Give your a nsw e r in te rm s of va ria ble s give n in the introduction.
= ANSW ER:
= Hin t 3. F rictional force
W hat is , the magnitude of the max imum forc e due to s tatic fric tion? Give your a nsw e r in te rm s of va ria ble s give n in the i...
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- Spring '10