Chapter-6 Work and Energy

1. Chapter-6Work and Energy

2. 6.1. Work Done by a Constant Force

3. 6.1. Work Done by a Constant Force

4. 6.1. Work Done by a Constant Force Work is done when a force F pushes a car through a displacement s.

5. 6.1. Work Done by a Constant Force Work is done when a force F pushes a car through a displacement s. Work = Force X Distance.

6. Work The work done on an object by a constant force F is:

7. Work The work done on an object by a constant force F is:

8. Work The work done on an object by a constant force F is: F = magnitude of the force, s = magnitude of the displacement, and θ = angle between the force and the displacement.

9. Work The work done on an object by a constant force F is: F = magnitude of the force, s = magnitude of the displacement, and θ = angle between the force and the displacement. SI Unit of Work: joule, J.

10. Units

11. Bench Pressing During bench-pressing work is done against gravity

12. 6.2 The Work-energy Theorem and Kinetic Energy

13. Work-Energy Theorem

14. Work-Energy Theorem

15. Kinetic Energy SI Unit of Kinetic Energy: joule (J)

16. Downhill Skiing A 58-kg skier is coasting down a 25° slope. A kinetic frictional force of magnitude 70-N opposes her motion. Near the top of the slope, the skier’s speed is 3.6 m/s. Ignoring air resistance, determine the speed vf at a point that is displaced 57-m downhill.

17. Downhill Skiing A 58-kg skier is coasting down a 25° slope. A kinetic frictional force of magnitude 70-N opposes her motion. Near the top of the slope, the skier’s speed is 3.6 m/s. Ignoring air resistance, determine the speed vf at a point that is displaced 57-m downhill.

18. 6.3 Gravitational Potential Energy

19. 6.3 Gravitational Potential Energy The gravitationalpotential energy PE is the energy that an object of massm has by virtue of its position relative to the surface of the earth. That position is measured by the height h of the object relative to an arbitrary zero level:

20. 6.3 Gravitational Potential Energy The gravitationalpotential energy PE is the energy that an object of massm has by virtue of its position relative to the surface of the earth. That position is measured by the height h of the object relative to an arbitrary zero level:

21. 6.3 Gravitational Potential Energy The gravitationalpotential energy PE is the energy that an object of massm has by virtue of its position relative to the surface of the earth. That position is measured by the height h of the object relative to an arbitrary zero level: SI Unit of Gravitational Potential Energy: joule (J)

22. Pile Driver Gravitational potential energy of the hammer relative to the ground is,

23. A Gymnast on a Trampoline A gymnast springs vertically upward from a trampoline. The gymnast leaves the trampoline at a height of 1.20 m and reaches a maximum height of 4.80 m before falling back down. All heights are measured with respect to the ground. Ignoring air resistance, determine the initial speed v0 with which the gymnast leaves the trampoline.

24. Problem-2, Page 174 The drawing shows a boat being pulled by two locomotives through a canal of length 2.00 km. The tension in each cable is 5.00 × 103 N, and theta = 20.0 degrees. What is the net work done on the boat by the two locomotives?