Some Photographs Related to Physics

[For Chapter on Measurements: SUNDIAL]
A sundial is a simple instrument to measure time, but its precision, accuracy, and range are very limited. (Ibitipoca Park, Minas Gerais, Brazil, 2004).

[For Chapter on Heat: CLOUD FORMATION]
Clouds form on a sunny day at the beach, due to air nearly saturated with water vapor rising to an altitude where the cooler temperature and lower pressure causes the air to reach saturation. Does this happen as easily if a high pressure weather system is present? (Nova Viçosa, Bahia, Brazil, 2004).

[For Chapter on Fluids: BOATS]
The large ship is constructed from materials more dense than water. How does it remain afloat? How does the volume below the water line compare to the total mass of the ship and its passengers? Does the same principle apply to the rubber dingy? (Porto Seguro, Bahia, Brazil, 2005).

[For Chapter on Equilibrium: YOGA]
Front Plank is a popular yoga position where one arm points forward. How do these yoga practitioners have to shift their bodies to remain stable? Does it depend on the right/left direction where the arm points? Try it! Where are their centers of mass located? (Porto Seguro, Bahia, Brazil, 2005).

[For Chapter on Electromagnetic Waves: RADIO ANTENNAS and RAINBOW]
According to the theory of James Clerk Maxwell, radio waves used for communications and the light in a rainbow are both forms of electromagnetic waves, travelling at about 3 x 10^8 m/s. If that is the case, why can't we see radio waves, or can we? What is it that distinguishes radio waves from light? (Campus of Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil, 2005).

[For Chapter on WAVES: BEACH WAVES]
Waves at a beach carry both kinetic and potential energy, properties common to all types of waves. Further, they can even exert forces and transfer momentum to other objects, such as the surfer! (Florianopolis, Santa Catarina, Brazil, 2005).

[For Chapter on Equilibrium: WOMAN BALANCING]
To hold a position, the net force and net torque on any body, using any axes, must be zero. How does it help to extand both and arm and a leg at the same time? Does it make her more stable? (Manhattan, Kansas, 2005).

[For Chapter on LIGHT AS WAVES or OPTICAL INSTRUMENTS: TULIPS]
Photography relies on the reflection of light off of objects, and letting that light pass through a lens to form an image on film or an electronic detector. But what aspect of the light determines the wide range of colors we experience? How does a camera "know" what color the light is? (Stockdale, Kansas, 2006).

[For Chapter on LIGHT AS WAVES: DOUBLE RAINBOW]
Rainbows appear when sunlight refracts through spherical water droplets. But it requires dispersion; the different colors of light have different wavelengths which travel at slightly different speeds inside the water droplets (index of refraction n depends on lambda), causing the colors to spread out. Did you notice the reversed colors in the secondary rainbow?! (Stockdale, Kansas, 2006).

[For Chapter on Heat: MAMMATUS CLOUDS]
During strong thunderstorms mammatus clouds can form at the base of supercells. Involving strong downdrafts, the formations illustrate convection -- movements of air and water vapor transfering heat between different altitudes in the clouds. The cottonball shapes change rapidly. Although appearing menacing, they do not pose any immediate danger. (Stockdale, Kansas, 2006).

[For Chapter on Heat: LAKE ICE]
When ice forms on a lake, it may not be perfectly smooth. Temperature changes cause expansion and contraction which leads to stresses and cracking. Do engineers need to worry about contraction of the steel in the bridge during winter, and if so, how do they accomodate it? (Tuttle Creek Reservoir, Riley County, Kansas 1994).

[For Chapter on ACCELERATION: FALLS]
Water going over a water falls undergoes acceleration due to gravity. How does the speed of the falling water increase with the distance it has fallen? How does the speed increase with the time fallen? (Unknown watefall, Brazil).