Apiece of spacecraft debris initially at rest falls to the earth's surface from a height above the earth equal to one-half of the earth's radius. find the speed at which the piece of debris hits the surface. neglect air resistance and the gravitational pull of the moon. express your answer with the appropriate units.

The us government wants to allocate billions of dollars in the next 10 years to assure our future energy security. the funds will be spread among a variety of possible energy resources. where do you think the government should put the greatest support: solar energy, wind energy, clean coal, oil exploration, gas exploration, or a combination of sources? are there other efforts that should be explored? support your position with cited information for both questions.

Your target variable is δf, the magnitude of the difference in frequency between the waves emitted from the sonar device and the waves received by the device after reflecting off the whale. write an expression for δf in terms of the relevant frequencies using the subscript notation introduced above.

The transfer of heat through the movement of a gas or liquid a. convection b. conduction c. radiation