Two drivers (driver A and driver B) are traveling in opposite directions on a long, straight road at different constant velocities. Their motions are represented by the position-time graphs of each, shown below. a)How long had driver A already been driving when driver B started to drive?

The atoms in a nickel crystal vibrate as harmonic oscillators with an angular frequency of 2.3 × 1013 rad/s. the mass of a nickel atom is 9.75 × 10-26 kg. what is the difference in energy between adjacent vibrational energy levels of nickel? (h = 6.626 × 10-34 j • s, , 1 ev = 1.60 × 10-19 j)