Mechanical Energy Physics Example 4

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Example 4

easy
A 4 kg4 \text{ kg} projectile has 200 J200 \text{ J} of kinetic energy at a height of 5 m5 \text{ m}. What is its mechanical energy? Use g=10 m/s2g = 10 \text{ m/s}^2.

Solution

  1. 1
    Given: KE=200 JKE = 200 \text{ J}.
  2. 2
    Gravitational PE: PE=mgh=4×10×5=200 JPE = mgh = 4 \times 10 \times 5 = 200 \text{ J}.
  3. 3
    Mechanical energy: E=KE+PE=200+200=400 JE = KE + PE = 200 + 200 = 400 \text{ J}.

Answer

E=400 JE = 400 \text{ J}
Mechanical energy is the sum of kinetic and potential energy. In this case the object has equal amounts of each, but the total stays constant throughout its flight (ignoring air resistance).

About Mechanical Energy

The total of kinetic energy and potential energy in a mechanical system at any given moment.

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Example 2 medium

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Example 3 medium

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