Two blocks are connected by a very light string passing over a massless and fric

Question

Two blocks are connected by a very light string passing over a massless and frictionless pulley (the figure (Figure 1) ). Traveling at constant speed, the 20.0-N block moves 80.0cm to the right and the 12.0-N block moves 80.0cm downward.

A)  During this process, how much work is done on the 12.0-N block by gravity?

B) During this process, how much work is done on the 12.0-N block by the tension in the string?

C) During this process, how much work is done on the 20.0-N block by gravity?

D) During this process, how much work is done on the 20.0-N block by the tension in the string

E) During this process, how much work is done on the 20.0-N block by friction?

F) During this process, how much work is done on the 20.0-N block by the normal force?

Please answer all parts! thanks

Explanation / Answer

A) W = F*S*cos theta = 12*0.8*cos(0) = 12*0.8 J
B)W = T*0.8*cos(180) = -12*0.8 J T=mg=12N because net force is zero on the block.
C) W = 20*0.8*cos(90) = 0
D) W = T*0.8*cos(0) = friction*0.8 J Force is zero, so T=friction
E) friction*0.8*cos(180) = -friction*0.8 J
Value of mew is needed for friction, so best leave it as variable.
F) 20*0.8*cos(90) =0 J

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