1. derive an expression for the energy needed to launch an object from the surface of earth to a height h above the surface.
express your answer in terms of some or all of the variables h, mass of the object m, mass of earth me, its radius re, and gravitational constant g.

2. ignoring earth's rotation, how much energy is needed to get the same object into orbit at height h?
express your answer in terms of some or all of the variables h, mass of the object m, mass of earth me, its radius re, and gravitational constant g.

1. what is the relationship between wavelength and the penetrating power of an electromagnetic wave? a) the penetrating power has no relationship to the wavelength. b) the penetrating power increases as the wavelength increases. c) the penetrating power decreases as the wavelength increases. d) the penetrating power decreases as the wavelength decreases. 2. as ice melts and turns into water, the speed of sound through the material would most likely do what? justify your answer. a) the speed would not change because the material is always water. b) the speed of sound would increase because the density of water is less than that of ice. c) the speed of sound would increase because energy is added to ice in order to make it melt. d) the speed of sound would decrease because sound travels faster through solids than liquids. 3.which of these waves need a medium to travel through? a) sound b) x-rays c) infrared rays d) visible light

What would be the radius of the earth if it had its actual mass but had the density of nuclei? express your answer to two significant figures and include the appropriate units.

Which of the following is a transformer used for? alternate a voltage produce a voltage increase or decrease a voltage eliminate a voltage