Energy Physics Example 1

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Example 1

easy
A 2 kg2 \text{ kg} ball is held 10 m10 \text{ m} above the ground and then dropped. What is its total mechanical energy at the top? Use g=9.8 m/s2g = 9.8 \text{ m/s}^2.

Solution

  1. 1
    At the top, the ball is at rest, so kinetic energy is zero: KE=0KE = 0.
  2. 2
    Potential energy: PE=mgh=2×9.8×10=196 JPE = mgh = 2 \times 9.8 \times 10 = 196 \text{ J}
  3. 3
    Total mechanical energy: E=KE+PE=0+196=196 JE = KE + PE = 0 + 196 = 196 \text{ J}

Answer

E=196 JE = 196 \text{ J}
Energy is the capacity to do work. Mechanical energy is the sum of kinetic and potential energy. At the top, all energy is stored as gravitational potential energy.

About Energy

The capacity to do work or cause change in a physical system, measured in joules (J).

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Example 3 easy

Name the energy transformations when a ball is thrown upward and comes back down.

Example 4 medium

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