If 40 kilograms of a radioactive element decay, so only 20 kilograms are left after 17 minutes, how much (in kilograms) will be left after 17 more minutes (for a total of 34 minutes)?

The entire apparatus in the figure below is at rest. Describe the forces acting on each box. Name each force and give a number with units for each force. There should be six forces in total.

For the same change in momentum, if the time a force is applied is larger, then the force must be ______________.

What are three ways to increase the voltage produced by moving a magnet through a coil of wire? 

List the three methods for softening hard water. 

Briefly describe heat conduction.

Which of the following is not dependent on sunlight as a source of energy?

No two species can occupy the same niche indefinitely without competition driving one to ________.

The kidneys are important homeostatic organs, contributing to the stability of all of the following except

What structure in the mammalian brain is enlarged and is responsible for higher mental processes?