Which sentence best describes the runner whose velocity-time graph is shown here? The runner ran forward for 2 seconds, and then backward for 2 more seconds.

The runner ran forward for 4 seconds - slowly for the first 2 seconds, then faster for the last 2 seconds.

The runner ran forward for 4 seconds - fast for the first 2 seconds, then more slowly for the last 2 seconds.

The runner stood still for 2 seconds, then moved suddenly, and then stood still again for 2 more seconds.

Around faucet handle is part of a(n) a. lever b. screw c. inclined plane d. wheel and axle

The particle in a two-dimensional well is a useful model for the motion of electrons around the indole ring (3), the conjugated cycle found in the side chain of tryptophan. we may regard indole as a rectangle with sides of length 280 pm and 450 pm, with 10 electrons in the conjugated p system. as in case study 9.1, we assume that in the ground state of the molecule each quantized level is occupied by two electrons. (a) calculate the energy of an electron in the highest occupied level. (b) calculate the frequency of radiation that can induce a transition between the highest occupied and lowest unoccupied levels. 9.27 electrons around the porphine ring (4), the conjugated macrocycle that forms the structural basis of the heme group and the chlorophylls. we may treat the group as a circular ring of radius 440 pm, with 20 electrons in the conjugated system moving along the perimeter of the ring. as in exercise 9.26, assume that in the ground state of the molecule quantized each level is occupied by two electrons. (a) calculate the energy and angular momentum of an electron in the highest occupied level. (b) calculate the frequency of radiation that can induce a transition between the highest occupied and lowest unoccupied levels.

Diamond will scratch quartz. true or false