A sports-car advertisement claims a maximum speed of

MATHEMATICS · Multi-part · A Level · Mathematics · Quantities and units in mechanics · Quantities and units in mechanics

Problem

250\,\text{km}\,\text{h}^{-1}

. Answer the questions that follow. (i) Express this speed in

\text{m}\,\text{s}^{-1}

. (ii) Express the same speed in

\text{cm}\,\text{s}^{-1}

. (iii) Calculate the percentage change in the numerical value of the speed when the unit is changed (a) from

\text{km}\,\text{h}^{-1}

\text{m}\,\text{s}^{-1}

, and (b) from

\text{m}\,\text{s}^{-1}

\text{cm}\,\text{s}^{-1}

. Explain the sign of the percentage change in each case.