WAEC Physics 2020 Paper

Concept:When the elevator accelerates upward, the weighing scale measures the apparent weight, which is the normal reaction $R$.Explanation:Given: mass $m = 60\,\mathrm{kg}$.Upward acceleration $a = 5\,\mathrm{ms}^{-2}$.Acceleration due to gravity $g = 10\,\mathrm{ms}^{-2}$.For upward acceleration, the apparent weight increases.The formula is:$$R = m(g + a).$$Substitute the given values:$$R = 60(10 + 5).$$$$R = 60 \times 15.$$$$R = 900\,\mathrm{N}.$$Answer:The reading of the scale is $900\,\mathrm{N}$.Therefore, the correct option is D.