AP Physics C 2017

Step 3 : Equations.

Notice how we have been careful to adhere to our convention of which forces act in the positive and
negative directions.

Step 4 : Solve.
Let’s solve for T using the first equation:

T = Mg −    Ma  .

Plugging this value for T into the second equation, we have

(Mg −   Ma  )   −   mg =    ma

Our answer is

A   2-kg    block   and a   5-kg    block   are connected   as  shown   on  a   frictionless    surface.    Find    the tension in  the

rope    connecting  the two blocks. Ignore  any friction    effects.

Why don’t you work this one out for yourself? We have included our solution on the following page.

Solution to Example Problem

Step 1 : Free-body diagrams.