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Catalyst

Catalyst. What is Newton’s 3 rd Law? Give me an example of the law?. Kinetic and Potential energy. Page 447. Go over homework. Pg 377 Data analysis Pg 377 questions 1-7. Energy: the ability to do work work is a transfer of energy measured in Joules= kgm 2 /s 2. Kinetic Energy.

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Catalyst

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  1. Catalyst • What is Newton’s 3rd Law? Give me an example of the law?

  2. Kinetic and Potential energy Page 447

  3. Go over homework • Pg 377 Data analysis • Pg 377 questions 1-7

  4. Energy: the ability to do work • work is a transfer of energy • measured in Joules= kgm2/s2

  5. Kinetic Energy • the energy of motion • kinetic energy of any moving object depends upon its mass and speed • equation: Kinetic energy= half the mass times the velocity squared • KE= ½ mv2 http://www.brainpop.com/science/energy/kineticenergy/preview.weml

  6. Practice Problem • A 0.10 kg bird is flying at a constant speed of 8.0 m/s. What is the bird’s kinetic energy?

  7. More Practice Problems • A 20kg dog is running at a constant speed of 16 m/s. What is the dog’s kinetic energy? • A 50 kg human is walking at a constant speed of 4 m/s. What is the human’s kinetic energy? • A human has a kinetic energy of 3.1 J, and a speed of 2.7m/s. What is the human’s mass? • A car has a kinetic energy of 6.3 J, and a speed of 5.4 m/s. What is the car’s mass?

  8. Potential Energy • energy that is stored as a result of position or shape. http://www.brainpop.com/science/energy/potentialenergy/preview.weml

  9. Gravitational Potential Energy • potential energy that depends upon an object’s height • an object’s gravitational potential energy depends on its mass, its height, and the acceleration due to gravity. • Potential energy (PE) = mgh • g (on earth) = 9.8 m/s (N)

  10. Practice Problem • Suppose the diver at the top of a 10.0 meter high diving platform has a mass of 50.0 kilograms. You can calculate her potential energy relative to the ground.

  11. More Practice Problems • A bird is sitting on top of a 17 meter high tree branch. The bird has a mass of 2 kg, what is its potential energy relative to the ground? • A jaguar is sitting on a tree branch 4.3 meters from the ground, waiting to attack its prey. The jaguar weighs 89kg, what is its potential energy relative to the ground? • The potential energy for a 2.5 kg squirrel in the tree is 1,500 J. At what height is the squirrel at? • The potential energy for a diver is 4,900 J. The diver is on top of a 15 meter high diving board. What is the mass of the diver?

  12. Other Forms of Energy • Mechanical energy: energy associated with the motion and position of everyday objects • the sum of the potential and kinetic energies • example: bouncing a ball, speeding trains etc

  13. Homework • Create a comic strip that either discusses the differences between • Kinetic energy and potential energy (include equations) • Newton’s 3 laws of motion

  14. Thermal Energy: • The total potential and kinetic energy of all the microscopic particles in an object. • example: when an object’s atoms move faster, it’s thermal energy increases and the object becomes warmer

  15. Elastic Potential Energy • The potential energy of an object that is stretched or compressed • Normally springs back to its original state

  16. Chemical energy: • energy stored in chemical bonds • burning gasoline

  17. Electrical energy: • energy associated with electrical charge • ex flashlights, cds

  18. Electromagnetic energy: • energy that travels through space in the form of waves • ex galaxies

  19. Nuclear energy: • energy stored in atomic nuclei • nuclear fission or nuclear fusion Practice problems: • Questions 6-9 pg 452

  20. Exit Ticket • Name and explain all of the energies needed to heat a cup of water

  21. Conservation of energy Page 453

  22. Conservation of Energy • Energy can be converted from one from to another • Energy conversion: the process of changing energy from one form to another.

  23. The law of conservation of energy states that energy cannot be created or destroyed

  24. Gravitational potential energy of an object is converted to the kinetic energy of motion as the object falls

  25. Energy conservation Equations • Mechanical energy = KE + PE • (KE + PE)beginning = (KE + PE) end • KE beginning = PE end • PE beginning = KE end

  26. Practice Problem • At a construction site, a 1.50 kg brick is dropped from rest and hits the ground at a speed of 26.0 m/s. Assuming air resistance can be ignored, calculate the gravitational potential energy of the brick before it was dropped

  27. More Practice Problems • At a playground, a 3.4 kg ball is dropped from rest and hits the ground at a speed of 28 m/s. Assuming air resistance can be ignored, calculate the gravitational potential energy of the ball before it was dropped. • At a hospital, a 1.8 kg stethoscope is dropped from rest and hits the ground at a speed of 14 m/s. Assuming air resistance can be ignored, calculate the gravitational potential energy of the stethoscope before it was dropped.

  28. Einstein’s equation E = mc2, says that energy and mass are equivalent and can be converted into each other. (c = speed of light 9 x 1013 J • energy is released as matter is destroyed, and matter can be created from energy.

  29. Practice Problems • 9 and 10 on page 459.

  30. Finish Newton’s Laws • Create a mini comic strip that explains and demonstrates • Newton’s 1st, 2nd, and 3rd laws

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