# University of Wisconsin Green Bay

## Physics Problems & Examples

Select an example physics problem from the list below. If you need more information, move your cursor around on the figures and solutions. Shaded boxes are links that show the relationship between figures and equations and that bring up explanatory text.

• #### Definition Problems These are straightforward problems that take you between two closely related concepts. Definition problems may be strictly mathematical (e.g. components of a vector), may involve rates (e.g. acceleration is the rate at which velocity changes), or they may simply be definitions (e.g. pressure is defined as force/area).

• #### Kinematics Also known as motion problems, these problems ask you to describe motion. Time is a key variable that tells you to work with the kinematic equations. If you are only asked for positions and velocities, you may also be able to work the problem using Conservation of Energy.

• #### Dynamics Dynamics (Force) problems ask you to relate motion to the forces causing it. Note that the word “force” isn’t always used explicitly in the statement of the problem. You know many forces such as gravity, tension, and normal force that are present even if not listed in the problem.

• #### Conservation of Energy These problems relate speed of an object at different positions. In order to work a problem using Conservation of Energy, you need to know either that there are no significant forces taking energy out of the system or the size of those forces. Conservation of Energy will not tell you about the time it takes to go between two positions.

• #### Electricity & Magnetism Electricity & Magnetism problems are often found in other categories. In addition to definition problems (e.g. electric force or field due to point charges), you use electric force in Dynamics problems and electric energy in Conservation of Energy problems. Unique to Electricity & Magnetism, however, are problems involving electric circuits or electromagnetic induction.

• #### Modern Physics Two areas of modern physics are addressed through example problems on this page. Special Relativity problems ask you to relate the observations of two observers measuring the same thing. In Quantum Mechanics problems, you may look at wave or particle behavior of light and subatomic particles. As always, basic definitions problems are found with other Definitions examples.

• #### Waves Whenever two waves of the same type are in the same place at the same time, they interfer with each other. This might happen when two waves are created and overlap, or when one wave reflects off of a new material (the reflected wave traveling in one direction interfers with the initial wave traveling in the other direction.) Standing waves are created when the waves always cancel in some places. In most problems, key words like “standing wave,” “interference pattern,” “diffraction pattern,” or “thin film” will initially tip you off to approach the problem through standing waves. This is also the physics behind musical instruments.