Frank says that if you release the string when swinging a ball in a horizontal circle, the ball flies out in the radial direction defined by the string at the instant you release the ball. John says that it flies out along a tangent line perpendicular to the string, and that it then drops straight down to the ground. 1. Which one, if either, is correct?
A. Frank, because the centrifugal force is no longer counteracted by the string.
B. Frank, because balls naturally fly straight out.
C. John, because there is no centrifugal force.
D. John, because balls fall straight down when released.
E. Neither, because although there is no centrifugal force, and the ball's velocity is tangent to the circle at the instant of release, the ball then follows a parabolic trajectory.
2. The tension in a string from which a 4.0-kg object is suspended in an elevator is equal to 44 N. What is the acceleration of the elevator?
a. 11 m/s^2 upward.
b. 1.2 m/s^2 upward.
c. 1.2 m/s^2 downward.
d. 10 m/s^2 upward.
e. 2.4 m/s^2 downward