Physics 151
April 3, 2013
Questions and Answers: 1. Define uniform circular motion. A. Is an object in uniform circular motion accelerating? B. Define centripetal acceleration, and state its magnitude and direction. (2.0 points) Ans: An object moving at a constant velocity around a circular path is performing a uniform circular motion. The object’s path is considered to be tangent to the circle due to the fact that it is constantly changing position as it goes around the circle. Therefore the velocity would also be tangent to the circle. [A] The object in uniform circular motion is experiencing acceleration due to the fact that is it changing direction constantly. [B] This is the centripetal acceleration. It’s directed towards the center of rotation. Is magnitude is calculated by V2r where v is the tangential velocity and r is the radius of rotation 2. A car is driven around a circular track. Which would have a greater effect on the magnitude of its acceleration, doubling the speed or moving to a track with half the radius? Please show your proof or calculations. (1.0 point) A. Define centripetal force (F c) ? B. Which object is providing the centripetal force in this experiment? Ans: Cense acceleration is given by V2r doubling the velocity has a greater effect then dividing the radius by 2. [A] The force the supply the acceleration is called centripetal force. This force is also always directed towards the center of rotation. [B] The object providing the centrifugal force in this experiment is the tention in the rope. 3. When you go around a corner in a car, do you feel centripetal or centrifugal (Fg) force acting upon you? (1.5 points) Ans: The car is experiencing centripetal force thus it does not “fly of “ the streat. 4. Explain why ∣F=mg∣ =∣Fc=4π2 M f 2 r∣in our experiment. (0.5 point) Ans: It worked because the balancing force is the tetion In the string which