Friction is a force that opposes motion. Manuel and his lab partner set up the incline you see here. One wooden board was left bare and the other was covered with carpet. The boys used a spring scale to pull blocks, of equal mass, up the incline. A force of of 2.5N was used to pull the block up the bare wood side; a force of 7.5N was used to pull the block up the carpeted side. Their data supported their hypothesis. Manuel and Kai set up another experiment to determine how different shapes impact the amount of friction needed to pull objects up the bare wooden board. They tested four objects of equal mass on the inclined wooden board. Predict in which trial would the friction force between the object and the wooden board be the LOWEST?