Changing position moves energy between spring and motion while the total stays exact.

Changing position moves energy between spring and motion while the total stays exact. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

At the endpoint the spring holds the full total

Position 4 m gives spring energy 16 J and kinetic energy 0 J. Their sum stays 16 J.

U+K=16 J+0 J=16 JU+K=16\ \mathrm{J}+0\ \mathrm{J}=16\ \mathrm{J}
Energy split scanSpring, kinetic, and total energy are checked.mUKk=2 N/mA=4 mx=4 mE=16 JU=16 JK=0 J

Half displacement leaves most energy kinetic

Position 2 m gives spring energy 4 J and kinetic energy 12 J. Their sum stays 16 J.

U+K=4 J+12 J=16 JU+K=4\ \mathrm{J}+12\ \mathrm{J}=16\ \mathrm{J}
Energy split scanSpring, kinetic, and total energy are checked.mUKk=2 N/mA=4 mx=2 mE=16 JU=4 JK=12 J

At the center all stored energy is kinetic

Position 0 m gives spring energy 0 J and kinetic energy 16 J. Their sum stays 16 J.

U+K=0 J+16 J=16 JU+K=0\ \mathrm{J}+16\ \mathrm{J}=16\ \mathrm{J}
Energy split scanSpring, kinetic, and total energy are checked.mUKk=2 N/mA=4 mx=0 mE=16 JU=0 JK=16 J