The work done by a spring is changing or constant?

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.

The speed of light in a material is 0.50 c. what is the critical angle of a light ray at the interface between the material and a vacuum?

Determine the maximum r-value of the polar equation r =3+3 cos 0