Find the total work done on 20.0N block

[bharp24]

Two blocks are connected by a very light string passing over a massless and frictionless pulley. The 20.0N block moves 75.0cm to the right and the 12.0N block moves 75.0cm downward.

Find the total work done on 20.0N block if there is no friction between the table and the 20.0N block.

Find the total work done on 12.0N block if there is no friction between the table and the 20.0N block.

Find the total work done on 20.0N block if static friction=0.500 and kinetic friction=0.325 between the table and the 20.0- block.

Find the total work done on 12.0N block if static friction=.500 and kinetic friction=.325between the table and the 20.0N block.

For the first two, I got total work done for both individual boxes to be 0J, but this is not correct somehow. I cannot really go on with the third and fourth scenarios until I get the first two. Can someone please help??

 

[Doc Al]

For the first two, I got total work done for both individual boxes to be 0J, but this is not correct somehow.

How did you determine this? What forces act on each block?

 

[bharp24]

i think i went ahead and added a friction force into the first 2, which zeros them out. i still get a wrong answer though when I leave the friction out. any suggestions on how to complete this problem?

 

[Doc Al]

Start by answering my question: What forces act on each block?

 

[bharp24]

i tried it again and got it right. thanks for trying to help me out!