A system consists of two particles. Particle 1 with mass 2.0 k g 2.0kg is located at ( 2.0 m , 6.0 m ) (2.0m,6.0m) and has a velocity of ( 3.1 m / s , 2.6 m / s ) (3.1m/s,2.6m/s). Particle 2 with mass 4.5 k g 4.5kg is located at ( 4.0 m , 1.0 m ) (4.0m,1.0m) and has a velocity of ( 1.1 m / s , 0.6 m / s ) (1.1m/s,0.6m/s). Determine the position and the velocity of the center of mass of the system.

According to the phase diagram for water, how is the state of water determined? proceed up a vertical line at any given temperature read the phase at the intersection of any given temperature and pressure at a given pressure, proceed horizontally to the s-l or l-g line

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.

For waves in the ocean, the medium of the waves is a. air b. water c. energy d. a passing boat