A simple pendulum consists of a 0.20 kg bob attached to a light string of length 0.80 m. The bob is released from rest at an angle such that its vertical height above the lowest point is 0.10 m. A partially completed energy bar chart is provided for three locations in one swing:
Location I: release point
• Gravitational potential energy: unknown height
• Kinetic energy: zero height
Location II: midway between release and the lowest point
• Gravitational potential energy: half the height of the bar at Location I
• Kinetic energy: unknown height
Location III: lowest point
• Gravitational potential energy: zero height
• Kinetic energy: unknown height
Ignore air resistance and internal friction in the string.
(a) Determine the numerical value of the gravitational potential energy at Location I with respect to the lowest point.
(b) Complete the bar chart by calculating the kinetic energy at Locations II and III.
(c) Using your result for Location III, determine the bob’s speed as it passes through the lowest point.
(d) Explain how the qualitative heights of the bars you calculated illustrate conservation of mechanical energy during the swing.