applied mechanics !!
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Re: applied mechanics !!
Re: applied mechanics !! -- ravindra.patil	Post Reply	Top of thread	Forum

Posted by: zekeman ® 01/19/2006, 22:33:28 Author Profile eMail author Edit

To absorb the energy, utilizing a motor you don't supply power, you absorb power;this is called dynamic braking. For example, if you use a DC PM motor in a generator configuration, you shunt the terminals with a resistance, R, and the rotational opposing torque is proportional to v/R, where v is the instantaneous angular velocity of the pulley. Then, since the energy differential equation is Td@=-d(mv^2/2)=-mvdv where @= angular displacement of pulley m=sum of the masses on pulley and since d@=vdt, T=kv v= instantaneous pulley angular velocity k= constnant t= time The differntial equation becomes dt=-m/kg(dv/v) which after integration yields a theoretical value of time of infinity. But practically, since coulomb and windage friction are present comes to rest more quickly. The more usual paramete r of interest is the stopping distance, @, which can be obtained using the first equation Td@=-mvdv kvd@=-mvdv d@=-m/kdv which very simply integrates to @=mV/k V is the intial angular velocity of the pulley= linear vel/pulley radius.

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Re: applied mechanics !!
Re: applied mechanics !! -- ravindra.patil	Post Reply	Top of thread	Forum

Posted by: Yates ® 01/16/2006, 04:35:48 Author Profile eMail author Edit

2mvsquared/tfifth power

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