Consider a 2 level system with ε_(1)=2.25x10^(-22) and ε_(2)=4.50x10^(-21)j.

a. at a temperature of 500k, which model (quantum mechanics of classical mechanics) is sufficient to describe this system and why?

b. if g_(2)=2g_(1) what value of t is required to obtain n_(2)/n_(1)=0.175?

c. at what temperature is quantum mechanics sufficient to describe the system?

Where is the potential energy throughout the loading, cocking, and releasing of the trebuchet?

What causes the formation of ocean currents?

Aparticle's position is given by x = 3.00 - 9.00t + 3t2, in which x is in meters and t is in seconds. (a) what is its velocity at t = 1 s? (b) is it moving in the positive or negative direction of x just then? (c) what is its speed just then? (d) is the speed increasing or decreasing just then? (try answering the next two questions without further calculation.) (e) is there ever an instant when the velocity is zero? if so, give the time t; if not, answer "0". (f) is there a time after t = 3 s when the particle is moving in the negative direction of x? if so, give the time t; if not, answer "0".