Which best describes the purpose of a controlled experiment?
to make sure the results of the experiment support the hypothesis

a. to prevent a dangerous condition resulting from a reaction

b. to examine whether one variable causes a change in another

c. to prevent an undesired change in a variable

Astone dropped into a well is heard to strike the water after 8seconds. find the depth of the well if the velocity of sound is 350m/s

Which graph represents motion with an object with positive velocity that is located at a position of 3 meters at a time of 0 seconds? a) a b) bb eliminate c) c d) d

Why is rain likely when warm, moisture-laden air meets cold air? a) the lighter warm air will rise and cool down, causing condensation and rain. b) the cold air moves faster and pushes the warm air away, causing condensation and rain. c) the moisture in the warm air condenses on contact with the cold air, causing rain to fall. d) the cold air mixes with the warm air, reducing its temperature causing moisture to condense.