Two velocities can be combined. Because of it, you must account for direction. The effects of the two velocities can be determined by doing what mathematical operation or vector math on the following: a. A surfer paddling with the current
b. A surfer paddling 90° to the current c. A surfer paddling against the current

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.

the answer is lactic acid from anaerobic respiration. the acid in lactic acid is what creates sore and burning muscles. if you think about how acid burns that will give you a clue for questions like this.

the correct answers are;

a. the rock was made from more than one type of material.

e. layers of hot liquids in the rock cooled and solidified at different temperatures.

these are the two options that are related to the statement given above.