4. A pendulum swings back and forth, reaching a maximum angle of 45" from the vertical. Which arrow shows the direction of the 45 45 P R pendulum bob's acceleration as it moves from left to right through #2 point @ (the low point of the motion)? #1 (A) #1 (to the left) (B) #2 (straight up) #3 (C) #3 (to the right) (D) #4 (straight down) #4 5. A particle moves along a circular path with the same starting and ending point. During this process, its average velocity is _ and its average speed is (A) zero; zero (B) zero; nonzero (C) nonzero; zero (D) nonzero; nonzero 6. To push a box up a ramp, in which case that the force required is smaller, push horizontally or push parallel to the ramp? (A) Horizontally (B) parallel to the ramp (C) the same