A rod of XY of weight 16N is hinged at X and supported by a string at Y. The string is at angle 30°. The tension in the string is 16N.

What is the horizontal component of the force acting at X?
(A) 8N
(B) 9N
(C) 14N
(D) 16N

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".