A student attaches a rope to a brick and pulls the brick across a rough surface at a constant speed. The forces that should be included in a free body diagram for the brick are: A) force of friction
B)normal force
C) gravity
D) tension force

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)