Physics 218: Mechanics Instructor: Dr. Tatiana Erukhimova Lecture 24

Ex.6 This is a one dimensional problem. A particle of mass m is attracted to the origin with a force of magnitude If a particle starts at x=A, moving to the right with velocity V 0, where will it turn around? Could there be no solution? x=0 x=A x V0V0

Quiz A block of mass m is placed at rest on a plane inclined at angle θ. After moving down L meters, it has velocity V 1. Find the coefficient of friction between the block and the plane.

Second exam Tuesday, October Heldenfels Section 801 and half of 802 start at 7 pm Section 803 and half of 802 start at 8:15 pm

Work Energy Theorem

If a force can be written as the gradient (slope) of some scalar function, that force is conservative. U(x) is called the potential energy function for the force If such a function exists, then the force is conservative 1D case:

does NOT depend on path! 1D case:

does NOT depend on path! If F x (x) is known, you can find the potential energy function as

or

Newton’s 2nd Law

Work does not depend on the choice of coordinates! You can calculate work of each force in the most convenient system of coordinates. Do not forget to work with components!

Usually there are several ways to solve the problem. Indicate the law or the theorem you use!

We will have a regular class on Wednesday!

Help Session: When: tonight at 7:10 pm Where: Room 202 James J. Cain Engineering/Physics Lab Building Spence St.

Have a great day! Hw: Be prepared for the test Good luck!