4 The displacement of a particle from a fixed point \(O\) at time \(t\) seconds is \(t ^ { 4 } - 8 t ^ { 2 } + 16\) metres, where \(t \geqslant 0\).
- Verify that when \(t = 2\) the particle is at rest at the point \(O\).
- Calculate the acceleration of the particle when \(t = 2\).