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 0 = 128º. 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??

In a thunderstorm, charge builds up on the water droplets or ice crystals in a cloud. thus, the charge can be considered to be distributed uniformly throughout the cloud. for the purposes of this problem, take the cloud to be a sphere of diameter 1.00 kilometer. the point of this problem is to estimate the maximum amount of charge that this cloud can contain, assuming that the charge builds up until the electric field at the surface of the cloud reaches the value at which the surrounding air breaks down. this breakdown means that the air becomes highly ionized, enabling it to conduct the charge from the cloud to the ground or another nearby cloud. the ionized air will then emit light due to the recombination of the electrons and atoms to form excited molecules that radiate light. in addition, the large current will heat up the air, resulting in its rapid expansion. these two phenomena account for the appearance of lightning and the sound of thunder. take the breakdown electric field of air to be eb=3.00ă—106n/c. part a estimate the total charge q on the cloud when the breakdown of the surrounding air is reached. express your answer numerically, to three significant figures, using ďµ0=8.85ă—10â’12c2/(nâ‹…m2) .

Describe uniform velocity and variable velocity in short

In order to do work, the force vector must be question 1 options: in a different direction than the acceleration vector. in a different direction than the displacement vector. in the same direction as the displacement vector and the motion. in the same direction as the acceleration vector.