Circular-Motion Online

P h y s i c s L a b 4 ( O n l i n e S i m u l a t i o n ) Introduction: We have seen the kinematics equations for translational motion in “Kinematics in one dimension” simulation. In this simulation we are dealing with rotational kinematics. If the motion is pure rotation, the equations can easily be rewritten by changing the translational symbols to rotational. The symbols and the rotational kinematics equations are given below. Angular displacement: units used for angle are degrees and radians. Linear quantities can be related to angular quantities as shown in the table to the left. Procedure I - Uniform Circular Motion: Open Ladybug Revolution http://phet.colorado.edu/simulations/sims.php?sim=Ladybug_Revolution 1. Click “Reset All” and check the position of the ladybug on the turntable. Set the angular velocity in such a way that the turntable moves clockwise. What are the directions of velocity and accelerations after the turntable rotates 180 0 ? R a R a t ¿ d / dt ¿ d / dt ❑ = ¿ t ❑ = ¿ t ¿ ❑ 0 + ❑ ( t − t 0 ) ¿ ❑ 0 + ❑ ( t − t 0 ) ❑ 2 = ❑ 0 2 + 2 ❑ ( x − x 0 ) ¿ ❑ 0 + ❑ 0 ( t − t 0 ) + 1 2 ❑ ( t − t 0 ) 2 As you see the figure on the left, the ladybug is located R from the center of axis of rotation. Its tangential Translational Angular Displacement x  x =  R Velocity v  v t =  R Acceleration a  a t =  R

P h y s i c s L a b 4 ( O n l i n e S i m u l a t i o n ) 4. Apply the following settings for the simulation and draw the graph you obtained in the space provided. a. Click “Reset All” and put the beetle at (2.5, 0) position b. Set the angular velocity to 20 rad/s c. Set the angular acceleration to 1 rad/s 2 d. Run the simulation for 10 seconds Follow-up Concept Questions: 1. Describe the directions of tangential velocity and accelerations for the following scenario. Support your answer with simple sketch a. A bug on a platform spinning counterclockwise with constant speed While the acceleration angle points towards the center, the velocity of the ladybug spinning counterclockwise with a constant speed has it pointing outwards. b. A bug on a platform spinning clockwise with constant speed In this scenario, it would be the same as scenario a, however the directions are just opposite. c. A ladybug is clinging to the rim of a wheel, which is spinning counterclockwise and is speeding up. a. What is the angular accelera tion? The angular accelera tion is 1.4 deg/sec ^2 b. What is the angular velocity at t=0? The angular velocity at t=0 is