PHYSICS 151 Chapter Work: 02 Physics review Work Dot product & Power

• School: UMASS-Amherst
• Department: Physics
• Course: PHYSICS 151
• Professor: Jason Stevens

Document Summary

Use to find the angle between two vectors. The dot product of two vectors results in a scalar value. Mechanical transfer of energy to or from the system, does not include thermal energy. W < 0 the e(cid:374)(cid:448)iro(cid:374)(cid:373)e(cid:374)t does (cid:449)ork o(cid:374) the syste(cid:373), syste(cid:373)"s e(cid:374)ergy i(cid:374)creases. W > 0 the system does work on the environment, syste(cid:373)"s e(cid:374)ergy decreases (cid:1827) (cid:1828)=(cid:1827)(cid:1828)(cid:1855)(cid:1867)(cid:1871) Unit of work is the unit of energy. Force does work only if object is displaced (cid:883)(cid:1865)=(cid:883)(cid:1836) A force perpendicular to the motion does no work. The friction force on a car turning a corner does no work. Neither does the tension force when a mass on a string is in circular motion (as long as speed remains constant). Work is positive if the force is in the direction of motion, negative if opposite that direction. W1+w2+w3=0 means no net work, occurs when moving at constant speed.