Probing the misconception:

 Students often fail to see the kinematical constraint of a string connecting two accelerating objects.

References Description

 

Compare the acceleration of the red block to the blue block in each of the cases shown below. In cases a and b, a constant force is pulling on the rightmost string.

a.  

b.

c.

 

Since each of the blocks (in each of the cases) is connected by a string, the red block must be undergoing the same acceleration as the blue block (or the string would have to be stretching).

 

 

 

 

 

 

 


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