You use a 1-foot basketball and a 3-inch orange as your earth and moon. about how far apart must they be placed to represent an accurate scale model of the earth-moon orbital system?

Some gamma ray bursts are hypothesized to come from mergers of neutron stars or black holes. if this hypothesis is correct, what else should we in principle be able to detect from such mergers? a. gravitiational waves b. x-ray bursts c. significant disruption of gas thousands of light-years away in the surrounding galaxy d. an "afterglow" of bright visible light, lasting for weeks

All of the following occurred due to the invention of the railroad except

How far is a geographic second? a.) around 100 feet b.) around 1,000 feet c.) around 5,000 feet d.) none of the above