Important Equations: KE = 12 Mv2 Peelastic = 12 Kx2 Pegrav = Mgh P = Mv I = Favδt = Δp

Leader: Song Worksheet #11 Course: PHYS 111 Supplemental Instruction Instructor: Furukawa Iowa State University Date: October 5, 2016 2 2 Important equations: KE = mv ；PEelastic = kx ；PEgrav = mgh；p = mv；I = FavΔt = Δp. 1. (T/F) In uniform circular motion, the speed is constant, but the direction of the velocity vector is not constant.

2. (T/F) The direction of the centripetal force always points toward the center of the circle.

3. (T/F) On an unbanked curve, the kinetic frictional force provides the centripetal force.

4. In the game of tetherball, the struck ball whirls around a pole. In what direction does the net force on the ball point? A) toward the top of the pole B) toward the ground C) along the horizontal component of the tension force D) along the vertical component of the tension force E) tangential to the circle

5. Two equal-mass rocks tied to strings are whirled in horizontal circles. The radius of circle 2 is twice that of circle 1. If the period of motion is the same for both rocks, what is the tension in cord 2 when compared to cord 1? A) T2 = ¼T1 B) T2 = ½T1 C) T2 = T1 D) T2 = 2T1 E) T2 = 4T1

6. What is the greatest speed the car can have in the corner without skidding?

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