Two spaceships pass one another in opposite directions a a relative speed of 0.8c. an observer in spaceship 1 measures the length of spaceship 2 to be three fifths the length of her own ship. a) what is the ratio of the rest lengths of the two spaceships? b) what will an observer in spaceship 2 determine as the length of spaceship 1?

Abody of weight 60 kg is standing in a lift the lift going upward with a uniform velocity of 4.9 metre per second slows down and stops in two seconds then apparent weight of the body during the slow down process is

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

When an object is heated it contracts. a. true b. false