The mass of matts head is 5 kg and its centre of mass (A) is located LHead = 30 mm anterior to the axis of rotation (atlanto-occipital joint, B) acting at an angle of 90°. The neck extensors act LNeck = 52 mm posterior to the axis of rotation, at an angle of 𝜃
θ
= 128°. Matt is currently holding his head still. How much force do the neck extensor muscles need to produce to keep the head from nodding (i.e. keep his head still). Assume gravity is 9.8 m.s-2?