When it is completed in 2002, the International Financial Center in Taipei, Taiwan, will be the tallest building in the world. The International Financial Center will also have the fastest elevators in the world. Two of the 63 elevators will travel from the ground floor to the eightyninth floor in just 39 s. Suppose the power output of each elevator motor is 158 kW. How much work will these motors do in lifting the elevator to the eighty-ninth floor?

Adding more pulleys to a system of pulleys needed to lift an object. a. increases the force b. decreases the force c. increases the amount of work d. decreases the amount of work

Which simple machine is not part of this compound machine? a. lever b. pulley c. inclined plane d. wheel and axle

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