h. What will be the speed of the car at the bottom of the tunnel? 600, 802= 1 ( 1000kg) V 2 V= 34:64 m/s 16. If there aren't any non-conservative forces acting on the car, then the gravitational potential and kinetic energies of the car may transferable ,but the total mechanical energy of the car will be_ the same 17. Suppose there was a non-conservative force of friction acting on the car. What would happen to the total mechanical energy of the car from the start of the track to the end of the track? the total mechanical energy will m = 0.010 kg not be conserved. yi = 0m - - -- STOP Model 3 (Application, 15 minutes) - Dart Pistol 0.050 m - A spring-loaded, toy dart pistol is pointed straight up as shown in the figure here. k = 100 N/m A 0.010 kg dart is loaded into the pistol. As the dart is loaded, it compresses the spring inside the pistol by a distance of 0.050 m. The elastic constant of the spring is 100 N/m. Let the top of loaded dart be at the position y; = 0 m. N = (force ) = kg. m/sz 18. Before the gun is fired. a. What is the initial (before the gun is fired) elastic potential energy of this system? Espring = = KX"= 2. 100 N/m. (0.05 m ) ? = 0.125 kg my 2 b. What is the initial (before the gun is fired) gravitational potential energy of this system? at Fg= mgh = 6.01kg) ( 9.8m/s')(-0. 05m)= = 0. 004 9 kgm/s" (o ]) c. What is the initial (before the gun is fired) kinetic energy of this system? EK = O as No velocity d. What is the total mechanical energy of this system before the gun is fired? ETotal= 0.125 + (- 0.0049 ) = 0.1201 J 267. the friction of 19 . What non-conservative forces may affect the motion of the dart once the gun is fired? the air resistance of the non-conservative forces may affect the motion of the dart. 8 287 4637 w 20. Suppose that the non-conservative forces you listed in question #18 can be ignored because they are small. a. What would be the total mechanical energy of this system when the dart reaches its maximum height after the gun is fired? 0. 1201 J b. What will be the elastic potential energy of this system when the dart is at its maximum height after the gun is fired ? Espring = 0, do *= um c. What will be the gravitational potential energy of this system when the dart is at its maximum height after the gun is fired? 248 Eg = mgh = do the height is oin d. What will be the kinetic energy of this system when the dart is at its maximum height after the gun is fired? EK = 01 12 0J [? ) e. What will be the maximum height of the dart? the max kaeight is 0.05 m Extension- 21. At what height will the dart in model 3 have its maximum kinetic energy? when Do the dat reaches yi? 22. What will be the elastic potential, the gravitational potential and kinetic energies at this height? 23. What will be the maximum speed of the dart after the gun is fired