Educational
10 min read

Thinking Like a Physicist... How to Solve Any Problem in Physics

What’s So Challenging?

Students often struggle in physics because the initial step of problem-solving can be particularly daunting. Physics problems typically require a deep understanding of fundamental principles and the ability to apply these principles to various scenarios. This means students must first identify which concepts are relevant to the problem at hand, which can be challenging without a solid grasp of the underlying theory.
Additionally, physics problems often involve multiple steps and require the integration of different pieces of information. Students might find it difficult to break down the problem into manageable parts and determine the correct sequence of steps needed to arrive at a solution. This process demands critical thinking and strategic planning, skills that may not come naturally to everyone.
Furthermore, the abstract nature of physics can make it hard for students to visualize the problem and understand the physical phenomena involved. Without a clear picture of what is happening, students may feel lost and unsure of how to proceed. This initial confusion can hinder their ability to start solving the problem effectively, ultimately impacting their overall performance in the subject.

Thinking Like A Pro

Professors and seasoned physicists mostly rely on one systematic approach to solve a wide range of physics problems. Those who have mastered this method may find it second nature and instinctual to apply these problem-solving steps without much conscious effort. If you’ve ever heard someone say “My professor is really smart, but they just can’t explain it in a way that makes sense to me...” the problem is most likely caused by a lack of communication in clarifying a single step in the problem solving procedure. The step is probably obvious to the seasoned professor, but unclear to someone with an untrained mind.

Learning this approach takes practice, commitment, and even years to master, but the ability to approach physics problems in a systematic way is a valuable skill that not only helps in academic settings but also in real-world applications where critical thinking and analytical skills are essential. Without further-ado it is my pleasure to introduce you to the systematic approach known affectionately by physicists as the Problem-Solving Procedure.

Step 1 - Understand The Problem

As obvious as it may seem, you must begin with a clear understanding of the problem at hand. Carefully read the problem statement and determine what is being asked.

Step 2 - Visualize The Situation

Physicists typically draw diagrams to visualize the problem, which can help in understanding the relationships between different physical quantities. They may introduce symbols to represent these quantities.

Step 3 - Label Knowns and Unknowns

Note all given information. Highlight, circle, or label the initial conditions, constraints, and given values, and identify the quantities that need to be found. This initial step is crucial as it sets the stage for the entire problem-solving process. Watch out for these easy to miss “givens”:

v_f = 0 m/s in a problem that states “the object comes to rest after an amount of time t.”

v_iy = 0 m/s in a problem that states “the object rolls off the table with a speed v.”

a = 0 m/s^2 in a problem that states “a block slides with a constant speed v.”

Step 4 - Identify the Physical Principles Involved

The next step involves identifying which fundamental principles, such as Newton's laws of motion, conservation of energy, or Maxwell's equations are most appropriate for the problem at hand. This mathematical representation allows for the application of analytical techniques to manipulate and solve the equations.

Step 5 - Choose Relevant Equations

The next step involves translating the physical situation into a mathematical framework and writing down relevant equations based on the principles identified in the previous step. It is best to write these equations in their most general form.

Step 6 - Simplify Equations

At this point, it is useful to simplify your equations to only include the known and unknown variables. This will help to clarify the remaining steps and expose any information you still need to identify.

Step 7 - Isolate the Unknown Variable (algebraically!)

Finally, physicists solve the equations using appropriate mathematical methods, which can range from algebraic manipulations to calculus, depending on the complexity of the problem. For most physics problems, this step involves solving for the variable you’re looking for. The benefit of keeping numbers out at this point is to see if any variables “cancel out” or may prove unnecessary. This is also a good time to explore the relationships between different physical quantities in the equation. Does increasing the coefficient of kinetic friction affect the required force in a way that makes sense?

Step 8 - Substitute in Known Values

The hard work is behind you, it’s the calculator’s turn. Plug in all necessary values and compute the unknown quantity.

Step 9 - Interpret Your Result

They perform calculations methodically, often checking their work at each step to avoid errors. Once a solution is obtained, physicists interpret the results in the context of the original physical problem. They assess whether the solution is reasonable and consistent with the physical laws and given conditions. If necessary, they may approximate or refine their answer. This systematic approach not only helps physicists solve problems effectively but also deepens their understanding of the underlying physical concepts.

  • The steps typically include identifying the given information, determining what needs to be found, selecting the appropriate equations or principles to apply, and finally solving for the unknown.
  • Through practice and repetition, students can develop a strong problem-solving skill set that allows them to tackle even complex physics problems with confidence.
  • check the “limits” of the problem (i.e. if an independent variable (like mass) goes to infinity what happens to the dependent variable? The result should align with your intuition.)

This systematic approach will not only helps students solve problems effectively but also deepen their understanding of the underlying physical concepts. Through practice and repetition, students can develop a strong problem-solving skill set that allows them to tackle complex physics problems with confidence.