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Difficulty: EasyWork, Energy, and Power

A pendulum bob is pulled to its highest point and released from rest. As the bob swings downward toward the lowest point of its path, which of the following energy transformations occurs?

  1. A
    Kinetic energy is converted into gravitational potential energy.
  2. Gravitational potential energy is converted into kinetic energy.Answer
  3. C
    Chemical energy is converted into thermal energy.
  4. D
    Gravitational potential energy and kinetic energy both decrease simultaneously.

Answer

Gravitational potential energy is converted into kinetic energy.
At the highest point of its swing, the pendulum bob possesses maximum gravitational potential energy due to its position and zero kinetic energy because its velocity is zero. As it falls downward toward the lowest point, gravity accelerates the bob, converting its stored gravitational potential energy into kinetic energy.

Step-by-Step Solution

1
Identify the initial energy state at the highest point of the swing.
At the peak, the pendulum bob has maximum gravitational potential energy (PE=mghPE = mgh) and zero kinetic energy (KE=0KE = 0) because it is momentarily stationary.
Gravitational potential energy depends on the height of the object above its reference level.
2
Analyze the energy change as the bob descends toward the lowest point.
The bob loses height, which decreases its gravitational potential energy, and accelerates downward, increasing its kinetic energy (KE=12mv2KE = \frac{1}{2}mv^2).
By the law of conservation of mechanical energy, the lost potential energy transforms directly into kinetic energy.

Key Concept

Conservation and Transformation of Mechanical Energy
Estimated Time:45s
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Topics

Work, Energy, and Power

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