Acceleration is the rate of change of velocity of an object with respect to time. It is a vector quantity, which means it has both magnitude and direction. When an object accelerates, it is either speeding up, slowing down, or changing direction.
From Molecules to Organisms: Structures and Processes
Design a solution to a human problem by using materials to imitate how plants and/or animals use their external parts to help them survive, grow, and meet their needs (e.g., outerwear imitating animal furs for insulation, gear mimicking tree bark or shells for protection).