GCSE Combined Science (AQA)

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Kinetic & Elastic Conversions

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Forces Forces and elasticity

Kinetic & Elastic Conversions

4:35 Elastic Potential Energy
Spec 4.1.1.2 4.5.2 4.5.3
Previous Work & Elastic Potential Next Speed
  • When an object is stretched or compressed elastically, work is done to give it elastic potential energy.
  • Example: Stretching an elastic band converts chemical energy into elastic potential energy.
  • Upon release, elastic potential energy is converted to kinetic energy, increasing the object's velocity.
  • Assuming no energy loss, kinetic energy gained equals elastic potential energy stored.
  • In inelastic deformations, some energy is used to break bonds.
  • Elastic potential energy (Ee) is equal to half ke squared.
  • Kinetic energy (Ek) is equal to half mv squared.
  • Ee equals Ek, so half ke squared equals half mv squared.
  • Simplifying the equation involves canceling out the halves.
  • Example problem: A 0.6 kg stone is pulled back on a slingshot with 66 joules of elastic potential energy.
  • Calculate the speed of the stone when released.
  • Assume elastic stretching and negligible band mass.
  • Key information: mass = 0.6 kg, elastic potential energy = 66 joules.
  • Kinetic energy given to the stone is 66 joules.
  • Rearrange kinetic energy equation to solve for V squared.
  • V squared equals 2Ek divided by M.
  • Take the square root of both sides to solve for speed.
  • Substitute values: V = square root of (2 * 66 joules / 0.6 kg).
  • Result: 14.832 meters per second.
  • Round to two significant figures: 15 meters per second.

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