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A preview of one of the most important and novel features you will encounter here. The S.I.M. strategy is a systematic, conceptual approach to starting mechanics problems.

The first step in solving any problem is to develop an understanding of the situation and to conceptually plan your attack. For those new to physics, this first step is often the hardest! As with learning any new skill, when learning to solve real problems it is important to be systematic. Luckily, there is a simple systematic approach that is usually a useful strategy for starting a mechanics problem. This approach is the SIM Strategy at the heart of problem solving in MAPS pedagogy:

• S. Choose a system to consider.
  
  In every mechanics problem, you will choose to focus on the motion of one or more objects. These objects will make up the system under consideration. Sometimes this choice will be easy. For problems involving the motion of a single car or baseball or box, the car or baseball or box will be the system. Other times, the choice can be hard. When two boxes collide, you may want to focus on only one of the boxes, or both independently, or you may want to consider them together as one system. Or you may decompose the system into intervals where first one and then another treatment is best.

• I. Describe the interactions this system experiences.
  
  Interactions are influences that change the motion of the system. The most common way to describe interactions is to think of them as forces and represent them using a free body diagram, but later you will become familiar with energy and torque as alternate descriptions. There are only a few types of interactions that we will study in this course, including gravity, contact forces (pushes, pulls, friction, etc.) and spring forces. It is important to recognize that interactions always occur between two objects. For instance, if your system is subject to a gravitational interaction, it must be near another object (often the earth). If your system is subject to a contact force, there must be another object nearby to do the pushing or pulling.

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