《大学物理》英文课件11 rolling, torque, and angular momentum教程文件.ppt

Rolling, Torque, and
Angular Momentum
Dr. Huaqiu Deng
E-mail: ******@scut.
Rolling as Translation and bined
Linear speed of smooth rolling motion:
Arc length and distance:
Rolling as Pure Rotation
Rolling as Translation and bined
The ic Energy of Rolling
Goal: to calculate the ic energy of rolling wheel of pure rotation about an axis of point P measured by a stationary observer.
Sample Problem
Problem: a uniform ball of mass M = and radius R rolls smoothly from rest down a ramp at angle θ= . (a) The ball descends a vertical height h = to reach the bottom of the ramp. What is its speed at the bottom? (b) What are the magnitude and direction of the frictional force on the ball as it rolls down the ramp?
Solution:
M = , θ= , h =
(a)
Sample Problem
Problem: a uniform ball of mass M = and radius R rolls smoothly from rest down a ramp at angle θ= . (a) The ball descends a vertical height h = to reach the bottom of the ramp. What is its speed at the bottom? (b) What are the magnitude and direction of the frictional force on the ball as it rolls down the ramp?
Solution:
M = , θ= , h =
(b)
The Yo-Yo
When a Yo-Yo rolls down or up the string, its ic energy( translational form (1/2) and rotational form(1/2)Icomω2) and potential energy (Mgh) exchange.