Heat can be transferred through conduction, convection, and radiation. what is necessary in order for heat to be transferred by conduction? a. the substances must be liquids or gases. b. the objects must be in direct contact with one another. c. heat must be transferred in the form of currents. d. heat must be transferred through space.

In an experiment examining the effects tai chi on arthritis pain, callahan (2010) selected a large sample of individuals with doctor-diagnosed arthritis. half of the participants immediately began a tai chi course and the other half (the control group) waited 8 weeks before beginning. at the end of 8 weeks, the individuals who had experienced tai chi had less arthritis pain that those who had not participated in the course.