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Work Grade 8

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Work Grade 8

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Work Grade 8

  1. 1. What is work  is an abstract idea related to energy.  when work is done it is accompanied by a change in energy.  a work is done when a force applied and distance travelled by an object is the same direction. is the product of force and distance. • W = Fd where, F = Force (N) d = distance (m)
  2. 2. A girl pushing a chair
  3. 3. A boy pushing a wall
  4. 4. A waiter carrying a tray
  5. 5. Calculating Work
  6. 6. Calculating Work Given: Force = 500 N distance= 7 m Work = ? Solution:
  7. 7. Solve the following problems:
  8. 8. Work is a method of transferring energy A ball and a plastic bottle
  9. 9. Work is a method of transferring energy A ball and a plastic bottle Is there a work done on the ball?
  10. 10. Work is a method of transferring energy A ball and a plastic bottle What can a moving ball do?
  11. 11. Work is a method of transferring energy
  12. 12. Solution: KE = 1 2 𝑚𝑣2 KE = 1 2 1000𝑘𝑔x(17𝑚/𝑠)2 KE = 1 2 1000𝑘𝑔x(289𝑚2 /𝑠2 ) KE = 1 2 289,000𝑘𝑔x(289𝑚2 /𝑠2 ) KE = 1 2 289,000𝑘𝑔 ∙ 𝑚2 /𝑠2 KE = 𝟏𝟒𝟒, 𝟓𝟎𝟎𝒌𝒈 ∙ 𝒎 𝟐 /𝒔 𝟐
  13. 13. Column B ___1. If you want to increase the kinetic energy of an object, you must increase its ____and _____ ___2. It is the ability to do work ___3. It means moving ___4. It is the energy of motion ___5. Energy is the ability to do ___. a. Work b. Energy c. Kinetic Energy d. mass and acceleration e. kinetikos
  14. 14. A Man lifting a box 0.5 m 2 kg Given: d = 0.5 m g = 9.8 𝑚 𝑠2 m = 2 kg PE = ? Solution: PE = mgh = (0.5m)(9.8 𝑚 𝑠2) 2kg = (4.9 𝑚2 𝑠2 )(2kg) = 9.8 Nm = 9.8 J
  15. 15. Column B ___1. It is energy at rest ___2. It is the ability to do work ___3. It means moving ___4. It is the energy of motion ___5. An acceleration of an object due to gravity. a. 9.8 𝒎 𝒔 𝟐 b. Energy c. Kinetic Energy d. Potential Energy e. kinetikos

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