9. A magnet moves at high speed relative to an observer and passes by an electron that is stationary relative to the same observer. At the instant the north pole of the magnet passes directly beneath the electron (as shown in Figure1), in which direction will the force acting on the electron point? (A) (B) 2 (C) 3 (D) 4

11. Consider the track shown in Figure 3. The track AB is one quarter of a circle of radius R=3.0(m) and is frictionless. The horizontal track from B to Chas a length of d=4.0(m) and a coefficient of kinetic friction =0.23. The track CD under the spring is frictionless. The track CD forms an angle θ=30° with the horizontal plane. A block with a mass of m=2.2(kg) is released from rest at point A. After sliding m along the track, it compresses the spring by 0.35 (m) and comes to rest at a distance 0.8 (m) from C. Determine the stiffness constant k for the spring. spring. (A) 610 (N/m) (B) 591 (N/m) (C) 554 (N/m) (D) 732 (N/m)

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