Edexcel A-Level Mathematics A2 M2.2.1 Centre of Mass of Discrete Distributions Questions

M( x axis)

M1

Need all terms. Dimensionally consistent. Condone if m missing throughout.

Accept as part of a vector equation

$$\begin{aligned} 2 m \times-+\times+\times=\times(2) 3 m 24 m 3 k \quad 9 m \quad x x=\frac{2+12 k}{9} * \end{aligned}$$

A1*

Obtain given result

2

M(y axis)
Need all terms. Dimensionally consistent. Might be seen as part of a vector equation in (a). It does not score any marks until referred to in part (b). Condone if m missing throughout.

$$\begin{aligned} 2 m \times+\times-+\times=\times 53 m(3) 4 m k \quad 9 m \quad y \square-14+k \square \square y=\square \square \end{aligned}$$
Correct unsimplified equation. Allow if m missing
throughout.

Form and solve equation in k
$$(2+12 k++=2 \quad 8 k \quad 27)$$
Use their y ānd $x \overline{+}^{-}=2 y^{-} \quad 3$

Dependent on the two preceding M marks

$k=\frac{23}{20}(1.15)$
Correct answer only

4

(6)