In which example is friction the most difficult to overcome? a. static friction between a desk and the floor b. rolling friction between a desk on wheels and the floor c. sliding friction between a desk and the floor once it is moving d. fluid friction between a moving desk and the air

Solar energy causes water to evaporate into the atmosphere. how does that water vapor become a cloud? a) as the water vapor goes higher in the sky, the air gets cooler. the cooler air causes the water vapor to condense. b) as the water vapor goes higher in the sky, solar energy causes it to condense around particles of dust. c) as the water vapor goes higher in the sky, the air gets warmer and the water vapor begins to condense. d) as the water vapor goes high into the atmosphere it turns to ice and that's what forms clouds.