Who first discovered why the earth and moon stay in orbit?

How is the introduction of the cane toad to queensland, australia an example of the unintended consequences of using non-native species to control pests? (site 1)

Achange in any of the following factors will cause investment spending and aggregate demand to change excepta. the interest rate effect b. expected business conditionsc. real interest rate d. expected future returns created by new technology e. expected business taxes

Analyze and evaluate the motivation and the rationale behind western expansion through the louisiana purchase that took hold in the united states at the start of the 19th century (long essay question)