Which of the following is not a characteristic of both surveys and experiments?
A. Data are collected about a population.
B. The data collected might be studied for patterns.
C. The researcher selects a sample of the population to study.
D. The researcher exercises direct control over at least one variable.

If a refrigerator is a heat pump that follows the first law of thermodynamics, how much heat was removed from food inside of the refrigerator if it released 380j of energy to the room?

The period of a pendulum varies directly as the square root of the length of the pendulum and inversely as the square root of the acceleration due to gravity. find the period when the length is 144 cm and the acceleration due to gravity is 980 cm per second squared, if the period is 7pi seconds when the length is 289 cm and the acceleration due to gravity is 980 cm per second squared.

At what time will the interfering waves have an amplitudeof zero?