The practice of science can answer only scientific questions. And scientific questions guide the design of investigations. What must be true of the
possible answers to a scientific question?
A. They support an established scientific theory.
B. They do not require the use of physical measurements.
C. They could be shown to be false by evidence.
D. They are at odds with established scientific theories.

Which of the following are used in an electrochemical cell? a. electrodes b. electrolyte c. terminals d. all of the above

Which pair of quantities includes one quantity that increases as the other decreases during simple harmonic motion?

Air enters a gas turbine with two stages of compression and two stages of expansion at 100 kpa and 17°c. this system uses a regenerator as well as reheating and intercooling – the intercooler returns the air to the inlet temperature. the pressure ratio across each compressor is 4 ; 300 kj/kg of heat are added to the air in each combustion chamber; and the regenerator operates perfectly while increasing the temperature of the cold air by 20°c. determine the system’s thermal efficiency. assume isentropic operations for all compressor and the turbine stages and use constant specific heats at room temperature. (0.378)