In 1987, a gargantuan iceberg broke away from the Ross Ice Sheet in Antarctica. It was approximately a rectangle with dimensions 154 km long, 35.0 km wide, and 250.0 m thick. What is the mass of this iceberg, given that the density of ice is 917 kg / m 3 ?

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".