Blocks A and B have masses m and 2m, respectively, and they are connected with the spring as shown. The spring is initially compressed and then the blocks are released. Which is the correct statement regarding the energy and momentum of the system? "

A)If the surfaces are rough, both the energy and momentum of the system are conserved
B)If the surfaces are smooth, both the energy and momentum of the system are conserved
C) If the surfaces are rough, only the momentum of the system is conserved
D) If the surfaces are rough, only the energy of the system is conserved
E)If the surfaces are smooth, only the energy of the system is conserved

Question

Blocks A and B have masses m and 2m, respectively, and they are connected with the spring as shown. The spring is initially compressed and then the blocks are released. Which is the correct statement regarding the energy and momentum of the system? "

A)If the surfaces are rough, both the energy and momentum of the system are conserved
B)If the surfaces are smooth, both the energy and momentum of the system are conserved
C) If the surfaces are rough, only the momentum of the system is conserved
D) If the surfaces are rough, only the energy of the system is conserved
E)If the surfaces are smooth, only the energy of the system is conserved

ayaan3232 · Answer

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ganeshie8 · Answer

The assembly consists of two blocks A and B which have a mass of 20 kg and 30 kg, respectively. Determine the distance B must descend in order for A to achieve a speed of 3m/s starting from rest.

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ganeshie8 · Answer

Few things first :

1) If B slides down by a length of $l_B$ meter, how far will A slide up ?

ganeshie8 · Answer

@ayaan3232

ayaan3232 · Answer

Yes

ayaan3232 · Answer

@ganeshie8  m confused in pulley lengths..

ganeshie8 · Answer

Suppose B slides down by $l$ meters

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ganeshie8 · Answer

The same length of rope must slide up from the left end : 
$x+x+x = l$
$x = ?$

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