A piece of black tape is now placed over the upper half of the lens. Which of the follow is true. a. Only the lower half of the object (i. e., the arrow tail) will show on the screen. b. Only the upper half of the object (i. e., the arrow head) will show on the screen. c. The whole object will still show on the screen.

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".