6. Isaac Newton was NOT inspired by the falling apple on his head. Actually, it was striking his stomach when he lay down. This apple was bounced back and upward straightly, and it lost 19% of its kinetic energy during the interaction. How high would the apple rise after the first bounce if it originally fell from a branch at a height of one meter? (Answers in meters) (A) 1.0 (B) 0.65 (C) 0.90 (D) 0.81 (E) 0.19.

2. Suppose a spring is massless, and it behaves well without exceeding the elastic limit (Hooke's law). One end of the spring is fixed at the center of a frictionless table. The other end of the spring is attached to a point solid ball of finite mass. This ball is in uniform circular motion around the center of the table. Which one of the following descriptions is true? (A) The square of the period of the ball is proportional to the cube of its distance from the center of the table. (B) The length of the spring is proportional to the speed of the ball. (C) The line joining the ball to the center of the table sweeps out equal areas in equal times. (D) The force acting on the ball is inversely proportional to the distance from the ball to the center of the table. (E) The point solid ball is in translational equilibrium, since its speed is constant.

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