Lab-6_Energy_Online

P h y s i c s L a b 6 ( O n l i n e S i m u l a t i o n )  E mech +  E th +  E int = 0 The skate park is an excellent example of the conservation of energy. For the isolated skate- track-Earth system, the law of conservation of energy equation has the form  E mech +  E th = 0 Mechanical Energy: The mechanical energy E mech of a system is the sum of its kinetic energy K and its potential energy U: E mech = K + U The conservation of mechanical energy can be written as  E mech =  K +  U = 0. It can also rewritten as K 1 + U 1 = K 2 + U 2 In which the subscript refer to different instants during an energy transfer process. Gravitational Potential Energy: The potential energy associated with a system consisting of Earth and a nearby particle is gravitational potential energy. If the particle moves from y 1 to height y 2 , the change in gravitational potential energy of the particle-Earth system is  U = mg(y 2 – y 1 )=mg  y Kinetic Energy: The kinetic energy is associated with the state of motion of an object. If an object changes its speed from v 1 to v 2 , the change in kinetic energy is  K = K 2 – K 1 = ½ mv 2 2 - ½ mv 1 2 Procedure: Open Energy Skate Park http://phet.colorado.edu/simulations/sims.php?sim=Energy_Skate_Park Part I: Friction Parabola Track 1. Click Reset and observe the energy bars as the skater moves back and forth. As the skater descends his kinetic energy (green) increases and his potential energy (blue decreases The total energy bar does not change -3 2. Considering the bottom of the parabola as a reference line, measure the maximum height (h) the skater climb. h = 3.83 -2 3. The gravitational potential energy at the maximum height is equal to 3500Joules. -2 4. The skaters speed at the minimum point of the parabola is equal to 2.92m/s. -2 5. Change the skateboarder (say Bulldog) and repeat steps 2, 3, and 4. -3 a. h = 3.82 m b. gravitational potential energy = 1000 Joules c. speed = 2.92 m/s 6. Is the law of conservation of energy affected by the mass of the skater? Yes/no. -2 7. Now click Reset and observe the Energy versus Position graph as the skater moves back and forth. Do not forget to put the reference line at the minimum point of the parabola a. Pause the simulation at the bottom of the parabola. -4 i. Kinetic energy = 3000Joules ii. Potential energy = 1000Joules b. Run the simulation again, and then pause it at the maximum height. -4 i. Kinetic energy = 0Joules ii. Potential energy = 4000 Joules 8. Apply the following settings for the simulation to answer the proceeded questions. a. Stop the simulation b. Click Reset then return skater buttons c. Adjust the coefficient of friction to one-eighth mark on the slide

P h y s i c s L a b 6 ( O n l i n e S i m u l a t i o n ) done? 5880