CurriculumGrade 8Science

Energy Transfer Changes Motion

Aligned to MS-PS3-5 — Next Generation Science Standards.

What this lesson teaches

An object's kinetic energy changes only when energy is transferred to or from it, usually by a force doing work. The energy is never lost — it just moves between objects or forms.

Worked example

When a soccer ball rolls to a stop, its kinetic energy does not vanish — friction transfers that energy to the ground and air as thermal energy, warming them slightly.

Practice questions

  1. Observe a ball speeding up down a ramp and identify where its added energy came from.
  2. Construct an argument, using evidence, that a slowing sled is transferring energy away.
  3. Explain why a moving object cannot speed up unless energy is transferred to it.

Watch the lesson

Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.

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En español

La Transferencia de Energía Cambia el Movimiento

La energía cinética de un objeto cambia solo cuando se le transfiere energía o se le quita, normalmente por una fuerza que realiza trabajo. La energía nunca se pierde — solo se mueve entre objetos o formas.

Ejemplo: Cuando una pelota de fútbol rueda hasta detenerse, su energía cinética no desaparece — la fricción transfiere esa energía al suelo y al aire como energía térmica, calentándolos un poco.

More Energy lessons

Kinetic Energy, Mass & SpeedMS-PS3-1Position & Stored Potential EnergyMS-PS3-2Designing for Heat TransferMS-PS3-3Mass, Temperature & Thermal EnergyMS-PS3-4

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