Moderate -0.3 This is a straightforward application of conservation of momentum in 2D. Students must equate total momentum before and after collision in vector form, then solve a simple linear equation for the unknown mass. The calculation is routine with no conceptual subtleties, making it slightly easier than average for M2.
A small ball \(A\) is moving with velocity \((7\mathbf{i} + 12\mathbf{j})\) ms\(^{-1}\). It collides in mid-air with another ball \(B\), of mass \(0.4\) kg, moving with velocity \((-\mathbf{i} + 7\mathbf{j})\) ms\(^{-1}\). Immediately after the collision, \(A\) has velocity \((-3\mathbf{i} + 4\mathbf{j})\) ms\(^{-1}\) and \(B\) has velocity \((6.5\mathbf{i} + 13\mathbf{j})\) ms\(^{-1}\).
Calculate the mass of \(A\). [4 marks]
A small ball $A$ is moving with velocity $(7\mathbf{i} + 12\mathbf{j})$ ms$^{-1}$. It collides in mid-air with another ball $B$, of mass $0.4$ kg, moving with velocity $(-\mathbf{i} + 7\mathbf{j})$ ms$^{-1}$. Immediately after the collision, $A$ has velocity $(-3\mathbf{i} + 4\mathbf{j})$ ms$^{-1}$ and $B$ has velocity $(6.5\mathbf{i} + 13\mathbf{j})$ ms$^{-1}$.
Calculate the mass of $A$. [4 marks]
\hfill \mbox{\textit{Edexcel M2 Q1 [4]}}