Why do sound waves move faster through the ground than through the air?
a. particles of matter are packed more loosely in the ground than in the air.
b. particles of matter are packed more tightly in the ground than in the air.
c. air doesn’t contain any particles of matter to transmit sound waves.
d. the elevation of the ground is lower than the elevation of the air space.

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

Abucket full of water weights 4 kg and water well is 10m deep. a girl draws water from the well. it takes the girl 3 minutes to draw a bucket full of water from the well. what is the power of the girl?

Aman throws a football straight into the air. as it rises, it slows down. which type of energy is the football gaining?