Factors affecting the speed of falling objects include weight, which is essentially gravitational force, and drag, which is air resistance. All objects have distinct mass, which typically remains constant as they fall. Provided mass does not change, the rate at which objects fall through the atmosphere is explained by Newton's second law of motion, which states that force equals mass times acceleration.
Weight and drag classify as vector quantities, and unlike mass, they can change. In the Earth's atmosphere, objects fall at different rates depending on their weight and the presence or absence of drag. Objects with higher weights, larger surface areas and high drag coefficients fall quicker than streamlined, lightweight objects.