Gravitational Potential Energy Physics Example 4

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Example 4

medium
A 0.5 kg0.5 \text{ kg} ball is thrown upward and reaches a maximum height of 12 m12 \text{ m}. What was the ball's kinetic energy at launch? Use g=10 m/s2g = 10 \text{ m/s}^2.

Solution

  1. 1
    At maximum height, all kinetic energy has converted to gravitational PE.
  2. 2
    PEmax=mgh=0.5×10×12=60 JPE_{\text{max}} = mgh = 0.5 \times 10 \times 12 = 60 \text{ J}.
  3. 3
    By conservation of energy, KElaunch=60 JKE_{\text{launch}} = 60 \text{ J}.

Answer

KElaunch=60 JKE_{\text{launch}} = 60 \text{ J}
At the peak, the ball is momentarily at rest, so all its initial kinetic energy has been converted to gravitational potential energy. Working backwards gives the launch KE.

About Gravitational Potential Energy

Energy stored in an object due to its height above a reference point in a gravitational field: PE=mghPE = mgh.

Learn more about Gravitational Potential Energy →

More Gravitational Potential Energy Examples

Example 1 easy

What is the gravitational potential energy of a [formula] book on a shelf [formula] above the floor?

Example 2 medium

A [formula] person climbs a [formula] ladder. How much gravitational PE do they gain? Use [formula].

Example 3 easy

At what height does a [formula] object have [formula] of gravitational PE? Use [formula].

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