Afather is pulling his child on a sled in the snow. according to newton’s third law, the force the father exerts
on the sled is equal to the force the sled exerts on the father but opposite in direction. how is it possible that the
father can pull the child and sled forward?

The space between two 15-in.-long concentric cylinders is filled with glycerin (viscosity = 8.5 × 10-3 lb·s/ft2). the inner cylinder has a radius of 1 in. and the gap width between cylinders is 0.1 in. determine (a) the torque and (b) the power required to rotate the inner cylinder at 180 rev/min. the outer cylinder is fixed. assume the velocity distribution in the gap to be linear.