What forces would slow down a marble if you were doing a roller coaster project, we know that friction is one, any other thoughts?

What would happen if the krill were removed from the food web

Cathy hypothesized that corn would not grow in mud. to test this hypothesis, she took corn kernels and placed 5 in mud, 3 in soil, and 2 in water. to her surprise, the kernels in the mud grew faster than the kernels in the soil. what error might have caused these unexpected results? a. wrong hypothesis b. not enough variables c. undefined control d. too many variables

What is the main fuel source for the work of the cell