Sandbox

Eq 1a: $$\mathbf{v}_2^A = \mathbf{v}_1^A + \frac{j}{M^A}\mathbf{n}$$

Eq 1b: $$\mathbf{v}_2^B = \mathbf{v}_1^B + \frac{j}{M^B}\mathbf{n}$$

Eq 2: $$(\mathbf{v}_2^A-\mathbf{v}_2^B)\cdot\mathbf{n}=-e(\mathbf{v}_1^A-\mathbf{v}_1^B)\cdot\mathbf{n}$$

Eq 3: $$\mathbf{v}_1^A\cdot\mathbf{n}+\frac{j}{M^A}\mathbf{n}\cdot\mathbf{n}-\mathbf{v}_1^B\cdot\mathbf{n}+\frac{j}{M^B}\mathbf{n}\cdot\mathbf{n}=-e\mathbf{v}_1^{AB}\cdot\mathbf{n}$$

Eq 4: $$j = \frac{-(1+e)\mathbf{v}_1^{AB}\cdot\mathbf{n}}{\mathbf{n}\cdot\mathbf{n}(\frac{1}{M^A}+\frac{1}{M^B})}$$