Students created models of the water cycle using empty plastic bottles. Water was placed in the bottom of each bottle, and the top was sealed with a plastic cap. The bottles were then placed in a sunny window in the classroom. What would best represent the precipitation step of the water cycle in this model?

water drops in the bottle collecting at the top

water drops in the bottle moving down the sides

the amount of water decreasing at the bottom of the bottle

sunlight from the window warming the water at the bottom of the bottle

Aspring has a relaxed length of 33 cm (0.33 m) and its spring stiffness is 6 n/m. you glue a 76 gram block (0.076 kg) to the top of the spring, and push the block down, compressing the spring so its total length is 15 cm. you make sure the block is at rest, then at time t=0 you quickly move your hand away. the block begins to move upward, because the upward force on the block by the spring is greater than the downward force on the block by the earth. calculate y vs. time for the block during a 0.09-second interval after you release the block, by applying the momentum principle in three steps each of 0.03-second duration.