Which statement(s) about galaxy groups is/are true?
choose one or more:
a. galaxy mergers in groups are not known to have ever happened
b. galaxies in a group are all moving away from each other.
c. interactions between massive and less-massive galaxies affect only the smaller galaxies.
d. tidal streams can result from galaxy interactions.
e. the largest galaxies tend to have satellite galaxies.

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

An object moves from position +34m to the position -15m in 15 seconds. what is the total displacement? what is the total velocity?

Use the information presented in the graph to answer the questions. which segments show acceleration? which segment indicates that the object is slowing down? what is the velocity of segment b? what is the acceleration of segment b?