A student creates a model of a sound wave coming from an object that is moving toward an observer to demonstrate the Doppler effect. Observer
- MED)
Using the model, which statement best describes the changes in the sound wave as it approaches the observer?
A The wavelength becomes longer and the pitch becomes lower.
OB The wavelength becomes longer and the pitch becomes higher.
C. The wavelength becomes shorter and the pitch becomes lower,
D. The wavelength becomes shorter and the pitch becomes higher

If a sphere and a cure have the same mass and are propelled up a ramp with the same force, which would travel father up the ramp? explain.

Antireflective coatings on solar cells are often made by applying a thin film of silicon nitride (sinx), which has an index of refractive of 1.2, on the top of the silicon solar cell, which has a refractive index of about 3.5. however, the sun emits radiation of various wavelengths which the solar cell absorbs, and the antireflective coating can only absolutely minimize the reflection of one of these wavelengths. the coating thickness is chosen to reduce the reflection of green/yellow light (e = 2.2 ev), which is the most intense color in the solar spectrum (shown below). which of the following coatings would minimize reflection of green/yellow light? the answer is 820 nm how? what is the angular width of the central maximum of an electron traveling at 2 x 108 m/s going through a single slit of width 1 mm.

Scientific models are based on current knowledge, which can limit their effectiveness when new discoveries are made.