1. Work The work done on an object by a constant force is given by: Units: Joule (J) The net work done on an object is the sum of all the individual “works”

2. x

3. x

5. Work-Kinetic Energy Theorem The net work done on an object: The kinetic energy of an object: The Work-Kinetic Energy Theorem:

8. Conservative vs. Nonconservative forces There are two general kinds of forces: conservative forces and nonconservative forces. A force is conservative if the work it does in moving an object between two points is the same no matter which path is taken. Gravity is a conservative force. Friction is a nonconservative force.

9. Gravitational Potential Energy The gravitational potential energy of a system consisting of the Earth and an object of mass m near the Earth’s surface is given by: Units: Joule (J)

10. What if there are no nonconservative forces (i.e. there is no friction)? Then W nc =0.

11. Conservation of Mechanical Energy In a system with no nonconservative forces, the total mechanical energy of the system remains the same at all times.

12. Spring Potential Energy This is also called the Elastic Potential Energy.

15. The spring force varies – it depends on x. So to figure out the work done by the spring force, we will use the average spring force.

16. Power If an external force is applied to an object and if the work done by this force is W in the time interval  t, then the average power is:

17. Work done by a varying force The work done by a variable force acting on an object that undergoes a displacement is equal to the area under the graph of F versus x.