which of these is true about the total amount of energy in a closed system?

decreases
destroyed and created
increases
remains the same

Two technicians are discussing how to test a car's exhaust by holding a small piece of paper within an inch of the tailpipe mouth. technician a says that if the paper is vibrating due to a "puffing" output from the tailpipe, this signals a smoothly running engine. technician b says that if the paper is being drawn toward the tailpipe, this could indicate burned exhaust valves. who is correct? a. technician b b. both technicians a and b c. technician a d. neither technicians a or b

What did pavlov initially notice about the animals in his original research after conditioning took place?

During a load test, a battery's voltage drops below a specified value. what action should the technician take?