Here again is the revised explanation from the previous question. In this version the sentences are numbered for easy reference.

Explanations Using Energy Ideas – Evaluating an Explanation

(1) The launched cart is moving toward the stationary target cart and when they collide there is a contact push/pull interaction between them. (2) The energy giver during this interaction is the launched cart, and energy is transferred from it to the target cart, which is the energy receiver. (3) Because of this energy transfer, the kinetic energy of the launched cart decreases while the kinetic energy of the target cart increases. (4) Since the target cart was initially at rest with a speed of zero and no kinetic energy, this increase in its kinetic energy means its speed is no longer zero, which in turn means that it starts to move.

Match the elements of a well-reasoned explanation with the sentence in which they occur.

A Establishes that an energy transfer occurs between the relevant objects.

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B Establishes which type of interaction is involved.

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C Explains that the transfer of energy leads to a change in a type of energy for the object(s) of interest.

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D Explains why a change of a certain type of energy leads to the observed outcome.

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