Motion Work and Mechanical Energy Review Inclined Planes

Motion Work and Mechanical Energy Review

Inclined Planes ● Two dimensional motion describes, o Two Dimensional Force Vectors such as with Inclined Planes o Motion in a Curved Path such as with Projectile Motion ● Weight of an object on an Inclined Plane is always acts downward mg

Weight Components on an Inclined Plane Fgx g(x) adjacent hypotenuse mg Fg(y) gy opposite

Acceleration in the y-direction y-axis x-axis FN Fg(x) hypotenuse adjacent Fg(y) Fg

Acceleration in the x-direction y-axis x-axis FN opposite Fg(x) hypotenuse Fg(y) Fg

Equilibrium

Mechanical Advantage

Lever I. M. A din Fout dout Fin fulcrum

Incline Plane I. M. A m d h

Pulley I. M. A The purpose of a pulley is to lift something up by applying a force down, it changes the direction. A single pulley does not change the magnitude of the input force. The tension force in the rope is distributed between individual pulleys. Thus the input force is magnified by a factor equal to the number of supporting rope segments. The tradeoff is that you must pull out twice as much rope as the increase in height F F F Pulley systems, with multiple pulleys, can have large mechanical advantages, depending on how they’re connected. 60 N Fin = F

Pulley cont. ,

Efficiency and Mechanical Advantage

Work Some work can be done against another force. • When you do push-ups, you do work against your own weight. Some work can be done to change the speed of an object. • Bringing an automobile up to speed or slowing it down involves work. In both categories, work involves a transfer of energy between something and its surroundings Version: 11. 19. 18

Mechanical Energy Version: 11. 19. 18

Potential Energy Version: 11. 19. 18

Work vs. Potential Energy The work/potential energy of the 100 -N boulder with respect to the ground below is 200 J in each case. a. The boulder is lifted with 100 N of force. b. The boulder is pushed up the 4 -m incline with 50 N of force. c. The boulder is lifted with 100 N of force up each 0. 5 -m stair. Version: 11. 19. 18

Work vs. Kinetic Energy Version: 11. 19. 18