Period 4 - GPE & KE Equations
•Download as PPTX, PDF•
0 likes•1,025 views
GPE & KE Equations
Recommended
More Related Content
What's hot
What's hot (11)
Similar to Period 4 - GPE & KE Equations
Similar to Period 4 - GPE & KE Equations (20)
More from ScientistKearns
Recently uploaded
Recently uploaded (20)
Period 4 - GPE & KE Equations
- 1. Question of the Day
- 2. Question of the Day
- 3. Today’s Objective: • You will be able to make calculations involving gravitational potential energy and kinetic energy.
- 5. Gravitational Energy g.p.e. = mg´h
- 6. Gravitational Energy Gay Wilkinson uses gunpowder to launch anvils up to 100 ft (30 m) into the air. Anvils weigh 100 lbs (the equivalent of 45 kg on Earth. How much energy does it take? https://www.youtube.com/watch?v=MLejkyXbJlc g.p.e. = mg´h
- 8. Kinetic Energy k.e. = 1 2 mv2
- 9. Kinetic Energy k.e. = 1 2 mv2 How fast does a 50 gram arrow need to travel to have 40 joules of kinetic energy? https://www.youtube.com/watch?v=1o9RGnujlkI
- 10. Elastic Energy
- 11. Elastic Energy e.p.e. = 1 2 kx2
- 12. Elastic Energy e.p.e. = 1 2 kx2 A bungee cord stretches 25 meters and has a spring constant of 140 N/m. How much energy is stored in the bungee? https://www.youtube.com/watch?v=mKIWQaW7z7Q
- 13. Conservation of Energy https://www.youtube.com/watch?v=mvA7AZEyciM How much energy did Renaud Lavillenie have at the highest point? (Assume his center of mass reached the highest point.)
- 14. Conservation of Energy https://www.youtube.com/watch?v=mvA7AZEyciM How fast did Renaud Lavillenie have to run to reach that height? (Assume no internal energy and the pole is weightless.)
- 15. Conservation of Energy How fast did Robbie Madison have to drive to reach the roof? https://www.youtube.com/watch?v=MLejkyXbJlc
- 16. Conservation of Energy https://www.youtube.com/watch?v=MLejkyXbJlc How fast was Robbie Madison moving when he landed?
- 17. Additional Practice: • Read p. 87 – 90 • # 6.15 – 6.21
Editor's Notes
- The answer is B. This question is taken from paper 12 of May/June 2012.
- The answer is B. This question is taken from paper 12 of May/June 2012.
- Remind the student that energy is the ability to do work. To transfer energy into a system, work needs to be done. Work = Force x Distance Remind the students that gravitational energy is energy stored in objects that have been raised. Ask how an object can be raised. (Lift it, put a force upwards.) Ask what force we would need. (A force equal to or greater than the weight.) Ask what distance it would move. (The height that is lifted.) Image from: http://ipolitics.ca/2015/01/30/why-you-really-need-to-stop-worrying-about-terrorism/
- Instruct that the gravitational potential energy is equal to the weight x height or mass x acceleration of gravity (on Earth) x height. Remind the students of period 1’s discussion: - If two objects have the same height, the one with more mass will hurt more (has more energy). - If two objects have the same mass, the one with more height will hurt more (has more energy). Ask the students what quantities they would need to calculate m. (g.p.e., g, and height.) Ask the students what quantities they would need to calculate h. (g.p.e., mass, and g.) Ask the students, if they were not on Earth, what quantities they would need to calculate g. (g.p.e., mass, and height.) Image from: http://ipolitics.ca/2015/01/30/why-you-really-need-to-stop-worrying-about-terrorism/
- 13,230 J or 13 kJ. It the class is strong, delete the quantities and let them watch the video twice. After the first time, state the question and discuss information that will be needed. Watch the video a second time and allow them to find and convert the units on their own in order to make the calculations. Video from: https://www.youtube.com/watch?v=IhQ4dE_RGnQ
- Remind the students of period 1’s lesson. Ask which two factors influences kinetic energy. (Mass and velocity.) Image from: http://www.scott-eaton.com/2010/bodies-in-motion-ii
- Instruct that the kinetic energy is equal to ½ mass x velocity^2. Remind the students of period 1’s discussion: - If two objects have the same speed, the one with more mass will hurt more (has more energy). - If two objects have the same mass, the one with more speed will hurt more (has more energy). Ask the students what quantities they would need to calculate v. (k.e. and mass) Ask the students what quantities they would need to calculate mass. (k.e. and v) Image from: http://www.scott-eaton.com/2010/bodies-in-motion-ii
- 40 m/s. Video from: https://www.youtube.com/watch?v=1o9RGnujlkI
- Remind the students of period 1’s lesson. Ask which two factors influences elastic energy. (spring constant and extension.) Image from: http://blogs.amdocs.com/network/2013/05/03/elastic-pcrf-stretch-data-services/#.VhO2As595yo
- Instruct that the elastic potential energy is equal to ½ spring constant x extention^2. Remind them that extension is not total distance, but distance stretched. Remind the students of period 1’s discussion: - If two springs have the same spring constant, the one that is stretched further will hurt more (has more energy). - If two springs are stretched the same distance, the one a larger spring constant will hurt more (has more energy). Ask the students what quantities they would need to calculate the spring constant. (e.p.e and extension) Ask the students what quantities they would need to calculate the extension. (e.p.e and spring constant.) Image from: http://blogs.amdocs.com/network/2013/05/03/elastic-pcrf-stretch-data-services/#.VhO2As595yo
- 43,750 J or 44 kJ. Video from: https://www.youtube.com/watch?v=mKIWQaW7z7Q
- 4,250.4 J or 4.3 kJ. Allow the students to request specific information: - His mass is 69 kg. - He vaulted 6.16 m. Source: https://en.wikipedia.org/wiki/Renaud_Lavillenie Video from: https://www.youtube.com/watch?v=mvA7AZEyciM
- 11.0 m/s Allow the students to request specific information: - His mass is 69 kg. - He vaulted 6.16 m. Source: https://en.wikipedia.org/wiki/Renaud_Lavillenie Video from: https://www.youtube.com/watch?v=mvA7AZEyciM
- 23.9 m/s (if he rose only to 96 feet); 26.8 m/s (if he rose to 120 feet) This problem challenges students because they must work with the equations without knowing the mass. Instruct the students to watch the video and determine how fast Robbie Madison had to drive to reach the roof and how fast he was moving when he landed. Again, students can ignore internal energy. Allow the students to request specific information: The height of the building is 96 feet (29.26 m). Robbie rose to a max height of 120 feet (36.6) before landing on the rooftop. His drop afterward was 80 feet (24.38 m). His mass is irrelevant. Source: https://en.wikipedia.org/wiki/Robbie_Maddison http://lasvegassun.com/news/2009/jan/01/motorcycle-daredevil-says-strip-injury-left-souven/ Video from: https://www.youtube.com/watch?v=MLejkyXbJlc
- 21.9 m/s This problem challenges students because they must work with the equations without knowing the mass. Instruct the students to watch the video and determine how fast Robbie Madison had to drive to reach the roof and how fast he was moving when he landed. Again, students can ignore internal energy. Allow the students to request specific information: The height of the building is 96 feet (29.26 m). Robbie rose to a max height of 120 feet (36.6) before landing on the rooftop. His drop afterward was 80 feet (24.38 m). His mass is irrelevant. Source: https://en.wikipedia.org/wiki/Robbie_Maddison http://lasvegassun.com/news/2009/jan/01/motorcycle-daredevil-says-strip-injury-left-souven/ Video from: https://www.youtube.com/watch?v=MLejkyXbJlc
- The additional practice can be found in the Cambridge IGCSE Physics (Second Edition) written by David Sang. More information about this coursebook can be found here: http://education.cambridge.org/as/subject/science/physics/cambridge-igcse-physics-%28second-edition%29/cambridge-igcse-physics-coursebook-with-cd-rom-%28second-edition%29