8. A soccer ball, at rest on the ground, is kicked with an initial velocity of 10 m/s at a launch angle of 30. Calculate its total ight time, assuming that air resistance is negligible. (A) 0.5 s (B) 1 s (C) 2 s (D) 4 s 9. A stone is thrown horizontally with an initial speed of 30 m/s from a bridge. Find the stone's total speed when it enters the water 4 seconds later, assuming that air resistance is negligible. (A) 30 m/s (B) 40 m/s (C) 50 m/s (D) 60 m/s 10. Which one of the following statements is true concerning the motion of an ideal projectile launched at an angle of 45 to the horizontal? (A) The acceleration vector points opposite to the velocity vector on the way up and in the same direction as the velocity vector on the way down. (B) The speed at the top of the trajectory is zero. (C) The object's total speed remains constant during the entire ight. (D) The vertical speed decreases on the way up and increases on the way down. A stone is thrown vertically upward with an initial speed of 5 m/s. What is the velocity of the stone 3 seconds later? (A) 25 m/s, upward (B) 25 m/s, downward (C) 35 m/s, upward (D) 35 m/s, downward A car travelling at a speed of vo applies its brakes, skidding to a stop over a distance of x m. Assuming that the deceleration due to the brakes is constant, what would be the skidding distance of the same car if it were traveling with twice the initial speed? (A) 2x m (B) 3x m (C) 4x m (D) 8x mThis question concerns the motion of a car on a straight track; the car's velocity as a function of time is plotted below. {) time (s) velocity (mix) I ._. r-'x hr' 2{l 1a) Describe what happened to the car at time t = 1 s. :b) How does the car's average velocity between time t = o and t = 1 5 compare to its average velocity between times t = 1 s and t = 5 s? :c) What is the displacement of the car from time t = o to time t = 7 s? :d) Plot the car's acceleration during this interval as a function of time. 1e) Make a sketch of the object's position during this interval as a function of time. Msume that the car begins at x = o. Consider a projectile moving in a parabolic trajectory under constant gravitational acceleration. Its initial velocity has magnitude v0, and its launch angle (with the horizontal) is 90. :a) Calculate the maximum height, H, of the projectile. b) Calculate the (horizontal) range, R, of the projectile. :c) For what value of 90 will the range be maximized? d) If 0