A3 m long plank with a weight of 130 n is placed on a dock with 1 m of its length extended over the water. the plank is uniform in density so that the center of gravity of the plank is located at the center of the plank. the boy with the weight of 180 in the standings plank and moving out slowly from the edge of the dock.
how far from the pivot point at the edge of the dock is the center of the plank?
what is the torque exerted by the weight of the plank about the pivot point at the edge of the dock? (treat all the weight as acting through the center of gravity of the plank).
how far from the edge of the dock can the boy move until the plank is just on the verge of tipping? round to the nearest hundredths place.

Awater-filled u-tube manometer is used to measure the pressure inside a tank that contains air. the water level in the u-tube on the side that connects to the tank is 5 ft above the base of the tank. the water level in the other side of the u-tube (which is open to the atmosphere) is 2 ft above the base. determine the pressure within the tank.

People with normal vision cannot focus their eyes underwater if they aren't wearing a face mask or goggles and there is water in contact with their eyes. in a simplified model of the human eye, the aqueous and vitreous humors and the lens all have a refractive index of 1.40, and all the refraction occurs at the cornea, whose vertex is 2.60 cm from the retina. with the simplified model of the eye, what corrective lens (specified by focal length as measured in air) would be needed to enable a person underwater to focus an infinitely distant object? (be careful-the focal length of a lens underwater is not the same as in air! assume that the corrective lens has a refractive index of 1.62 and that the lens is used in eyeglasses, not goggles, so there is water on both sides of the lens. assume that the eyeglasses are 2.05cm in front of the eye.)

A51 kg woman skis down a hill and her kinetic energy is 9.96e4 j. what is her speed?