1. Instructor: Dr. Tatiana Erukhimova
Physics 218: Mechanics
Instructor: Dr. Tatiana Erukhimova
Lectures 29,30,31

2. Polar coordinates

3. A ball of mass m is swung around a circle at the end of a string of length L. The string will break if the tension in it exceeds a critical value, Tc. What is the largest constant angular velocity the ball can have without breaking the string?

4. A ball of mass m is swung around a circle at the end of a string of length L. What is the minimum  the ball can have and still travel in a circle without string becoming slack?

5. A plane is flying in an arc at the speed of v0
A plane is flying in an arc at the speed of v0. At the top of arc the passengers experience a sense of weightlessness. What is the radius of the arc?

6. Rotational Motion
Whirling Beaker of Water

7. Platform rotates with angular acceleration (t)=t
Platform rotates with angular acceleration (t)=t. A man starts a distance L from the center and walks in along a straight line painted on the platform towards the center. He decreases his distance from the center as a constant rate, vc. What force does the platform exert on the man, as a function of his distance from the center?

8. A 3000 kg spacecraft is in a circular orbit 2000 km above the surface of Mars. How much work must the spacecraft engines perform to move the spacecraft to a circular orbit that is 4000 km above the surface?

9. A race track designer wants to have the cars able to maintain a speed vmax without skidding on a circular track. If the track is flat with a coefficient of friction  what does the radius have to be?

10. A frictionless track contains a circular section of radius R as shown
A frictionless track contains a circular section of radius R as shown. What is the minimum height at which a block must be started in order for it to go around the loop without falling off the track? H R

11. Conical pendulum

12. Kinematics

13. Have a great day! Reading: Chapter 12
Hw: All Chapters 12, 13 problems and exercises