1. A sailboat moves north for a distance of 20.0 km when blown by a wind from the exact southwest with a force of 3.50 x 10^4 N. The sailboat travels the distance in 2.5 h. a) How much work was done by the wind? b) What was the wind’s power? Your response should include all of your work and a free-body diagram. 2. A worker applies 170 N of force on a lever to lift a 1250 N crate 0.10 m. a) If the lever is 100% efficient, how far does he need to push his side? Your response should include all of your work.

3. A sailor pushes a 160.0 kg crate up a ramp that is 2.50 m high and 15.0 m long onto a loading dock. He exerts a 620.0 N force parallel to the ramp. a) What is the mechanical advantage of the ramp? b) What is the efficiency of the ramp? Your response should include all of your work and a free-body diagram.

The diagram shows a series of volcanic island and a hot spot determine the direction of movement of the tectonic plate that for the island

How does an observation about an object differ from an inference about that object

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.)