The Skate Park - Intro to Energy and Work

Name: The Skate Park - Intro to Energy and Work Lab % Introduction: When Tony Hawk wants to launch himself as high as possible off the half-pipe, how does he achieve this? The skate park is an excellent example of the conservation of energy. The law of conservation of energy tells us that we can never create or destroy energy, but we can change its form . In this lab, we will look at the conversion of energy between gravitational potential energy, work, and kinetic (or moving) energy. This conversion is work. ( Realize though , that in real life, skateboard wheels have friction. In our experiments, we ignore friction ) Energy is measured in units of Joules. - Important Formulas: KE =\mv 2 PE — ltlgh JV AE Energy Skate Park l Procedure: PheTSimulations Play With Sims Energy Skate Park Run Nowl I • Take some time and play with the skater and his track. • Click on the buttons to show the energy graphs and the pie graphs. These graphs show Energy Graphs 0 Plwth Thermd Bar Graph . Energy va Postton the conversion between kinetic energy (green) and potential energy (blue) If any . Energy vs Tma energy is lost, it will be shown with a red bar ( thermal energy tost ). | • Reset the skater to the standard half-pipe and observe the energy bars as he moves back and forth (without friction). • As the skater descends his kinetic energy (green ) change in kinetic energy is always I VTCFf CfiSrtd his potential energy (blue) JlCPffQ to the change in potential energy. The • Change the skater with l Choose Skoler .. I Is the law of conservation of energy affected by the mass of the skater? [\1 • Does mass of the skater affect the magnitudes of the kinetic and potential energy? V . Reset and drag the bottom on the half pipe to the bottom of the grid to set the lowest height to zero. Turn on the grid . Set the PhET skater (75kg) at 5.0m above the zero and allow him to skate. • • How much potential energy does he have at 5.0m? j • A 20.0 kg skater that starts his skate 10m high (on the earth) would have a potential energy of kinetic energy of and a kinetic energy of * J How much kinetic energy at 0.0 m ? v Q C and a before his skate. At the lowest point, the skater would have a potential energy of UPC- (hint: use the important formula for potential energy ) ^^ j q Create the skate paths as shown. If the skater starts on the left side, will he have enough energy to make it all the way to the right side? £ \* ZV\OJA4rfrl Why? / Why not? > LC\,[ AS E cf 'Conse ri/ U ) of £ If the skater starts on the left on the path here, match the letter here with the following conditions: 1. Maximum kinetic energy fe 2. Maximum potential energy A 3. Two locations where the skater has about the same speed CG 1 If the skater starts at the top of the ramp on the left, show how high will he be on the right side of the 3D to zoom out and increase the size of the ramp. ramp. Try this in the simulation. Press L — • Part II: Gravity’s affect on Energy Reset the skater and turn on the pie chart to show kinetic and potential energy. • Move the skater to Jupiter, where acceleration due to gravity is 26m/s2! Describe what happens to the skater’s ( P potential and kinetic energy . aV\aw\ vt V muMd 2 • Move the skater to the moon (g = 1.6 m/s ). Why is he moving like he is? 4Vyp , fiftYTV flP ft 1 ' J So ( oiAJ tf al (oiA£ \ MM 0 \TAMPI KlaMY faster- ^ • V + 0 • Zoom out LAJ increase the size of the ramp, and move the skate to SPACE! Press the arrow keys on your keyboard. Zoom out some more. Have fun . Is there potential (mgh) energy in space? Why / Why not? 0 Q\ [ l1 Is there kinetic (Vimv2) energy in space? Why / Why not? J Conclusion Calculations: (Vi pt each ) use g = 10. m/s2 Complete the table of kinetic and potential energies: height ( h ) Mass of skater (m ) velocity (v) Kinetic Energy ( KE) y 20. kg 14 m 60. kg 0.0 m 0.20 kg 18 m . 12 m/s * 5.0 kg nm ik » o Potential Energy ( PE) 2. 1400 J 0.0 m/s 5. 5.0 m/s 8 . 10. ^ 6.0 ^ /s -a 0$00 T 4. 1470 J 6.0 m |0 tO ) 1. • - 6 OT Wo- O T 6b tr m2 600. J 160 J ^ boo - w 850 J $50*5 lD - h Conclusion Questions: ( Vi pt each) use g = 10L m/s2 1. At the highest point kinetic energy \{ zerb maximum while the potential energy is zero / [ maximum . 2. At the lowest point kinetic energy is zero aximum hile potential energy i zerby maximum. ^ 3. Mass affects Z$oes notaffecfthe conservation of energy. 4. How much potential energy does the 60. kg skater have before she starts her ride, 12 m above the ground? 5. How much kinetic energy does a 60.0 kg skater have traveling with a velocity of 4 m/s? 6. How fast must a 20. kg skater travel to have a kinetic energy of 360 Joules? 4 8. How fast must the 2.0 kg basketball be thrown upward to achieve the same 160 J ? 31* 0 * 10 vQ 8,® ^ rnr i nt . b> 9. If a 75kg skater starts his skate at 8.0m, at his lowest point, he will have a velocity of /5 !V\ j S 1 ft. In the above question, all the potential energy became kinetic energy. How much work was done? AM S YA Ve ^fDoV, { j>OOD . O tn tX.- iDO'/ = J - '465 V * \£,OO03 ^^ 4 L&Cfto 7. How high must a 2.0 kg basketball be thrown so it has a potential energy of 160 J? 3 3 7 I < ipOOO 5 [ P \