A leaky exhaust system not only causes a loud noise but also: A. causes the motor to dangerously overheat B. gives out poisonous fumes that could get inside the car C. causes back pressure on the motor which could cause it to stall

Aparticle's position is given by x = 6.00 - 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".