Physics

Problem

On Earth, a mass of

2\,\text{kg}

stretches a certain vertical spring by

1.5\,\text{cm}

. The same spring is used inside a lift that is ascending with an acceleration of

2\,\text{m s}^{-2}

. If an unknown mass attached to the spring produces an extension of

2.1\,\text{cm}

in the lift, the mass is closest to a)

3.5\,\text{kg}

2.8\,\text{kg}

2.3\,\text{kg}

1.8\,\text{kg}