Asa watches her mom rub soap on her finger to help get a ring unstuck. He thinks that the soap reduces friction. He designs an investigation to test his theory. He pills a weight across a board and records the force with a spring scale. He then puts soap on the board and pulls the weight again. Which of the following variables is Asa measuring?

The horse latitudes-high-pressure zones about 30 degrees north and 30 degrees south of the equator.-warm air traveling away from the equator cools and sinks-weather tends to be clear and drythe doldrums-low-pressure near equator-air rises and spreads out toward the poles-rising moist air produces clouds and heavy rainthe westerlies-blow from the west-move from the horse latitudes toward the poles.-bring storms across much of the united statesthe tradewinds-blow from the east-move from the horse latitudes toward the equator  -strong, steady winds