As shown in the figure above, blocks A and B are connected by a massless string

Question

As shown in the figure above, blocks A and B are connected by a massless string that passes over the outer edge of a pulley that is a uniform solid disk. Block A has a mass of 7.00 kg. Block B has a mass of 7.00 kg. The pulley has a mass of 4.00 kg, and rotates without friction. When the system is released from rest, it experiences a constant (and non-zero) acceleration. Use g = 10.0 m/s2. You can solve this problem using constant acceleration methods, but try using energy methods instead.

(a) To start with, we will neglect friction between block A and the surface. When block B has dropped through a distance of 2.00 m, what is its speed?
m/s

(b) Now answer the same question, but use a coefficient of kinetic friction of 0.120 between block A and the surface.
m/s

Explanation / Answer

We can write the general Energy equation as: 0.5(Mbv^2+Mav^2+MpR^2/2(V/R)^2)=Mbgx-(coefficient of kinetic friction)Magx Where Ma,Mb,Mp denote mass of various Objects x is the distance moved by block B (which is equal to distance moved by block A) Also w=V/R v^2=2(Mbgx-(coefficient of kinetic friction)Magx)/(Mb+Ma+Mp/2) a)v^2=7g/4,v=4.14m/s b)v^2=7g/4.(0.88),v=3.884m/s

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