Three ropes are tied to a large boulder. The first rope is pulled with a force of 450 N due East while the second is being pulled with a force of 300 N at an angle 45° North-West. The third rope is being pulled with a force of 500 N 30° South-West.

Glass is transparent to visibile light under normal conditions; however, at extremely high intensities, glass will absorb most of the light incident upon it. this works through a process known as multiphoton absorption. in this process, several photons are absorbed at the same time. if very intense light whose photons carry 2ev of energy is shined onto a material with a band gap of 4ev, that light can be absorbed through two-photon absorption, because two photons have the right amount of energy to bridge the band gap. what is the minimum number of photons of 800-nm light that are needed to equal or exceed the band gap of fused silica glass

The transfer of heat through the movement of a gas or liquid a. convection b. conduction c. radiation

Which compound is held together by the electrostatic force between two ions? a. co2 b. cci4 c. h2s d. mgf2