Cold packs are designed to become very cold when activated. When the pack is activated, a chemical reaction occurs to make the temperature of the cold pack decrease. What must be true of this chemical reaction? (2 points) The reaction releases energy to its surroundings. The reaction releases energy to its surroundings. The products and reactants have the same amount of energy. The products and reactants have the same amount of energy. The products have less energy than the reactants. The products have less energy than the reactants. The reaction absorbs energy from its surroundings.

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.

This is the number of complete movements of a wave per second.

Panel bc in fig. p2.76 is semi-circular, with the 3 meter radius and horizontal straight edge through point b. compute (a) the hydrostatic force of the water on the panel, (b) its center of pressure, and (c) the moment of this force about point b. assume atmospheric pressure on the dry side of the panel