An experiment is conducted to determine how the arm length of a pendulum affects its period. the
experimental design calls for varying the length of the arm and the mass of the bob. which is true
about this experiment, based on good experimental design?
only the mass should be changed. the arm length should remain the same
the force applied to the mass should be varied for each trial
the material the arm is made of should be varied for each trial.
only the arm length should be changed. the mass should remain the same.

Because air contracts as it cools, the air pressure inside a freezer is typically lower than on the outside. why do ice cubes inside a freezer tend to shrink over time? a. the ice dissolves oxygen from the air, forming a denser crystalline matrix.b. the ice reacts chemically with carbon dioxide in the air, forming gaseous carbon compounds.c. the ice melts, and then the liquid freezes as ice crystals on the bottom of the freezer.d. the ice sublimes, and then the water vapor deposits as ice crystals on the sides of the freezer.