The specific heat capacity of steel is 450 J/kg?°C. Show that the amount of heat needed to raise the temperature of a 10-kg piece of steel from 0°C to 100°C is 450,000 J. How does this compare with the heat needed to raise the temperature of the same mass of water through the same temperature difference?

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".