questions

Units &amp; Modelling Assumptions

State whether each quantity described below is a scalar or a vector.
(i) The mass of a parcel is <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mn>2.4</mn><mtext> kg</mtext></mrow><annotation encoding="application/x-tex">2.4\text{ kg}</annotation></semantics></math>2.4 kg.
(ii) A train has velocity <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mn>12</mn><msup><mtext> m s</mtext><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow><annotation encoding="application/x-tex">12\text{ m s}^{-1}</annotation></semantics></math>12 m s−1 due east.
(iii) A machine operates for <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mn>18</mn><mtext> s</mtext></mrow><annotation encoding="application/x-tex">18\text{ s}</annotation></semantics></math>18 s.
(iv) A force of <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mn>35</mn><mtext> N</mtext></mrow><annotation encoding="application/x-tex">35\text{ N}</annotation></semantics></math>35 N acts vertically downwards.