Which of Newton's laws of motion states that force equals mass times acceleration?
Newton gave 3 famous laws of motion. The first law implies that a body at rest will continue to remain at rest and a body in motion will continue to be in motion until an external force is applied to it. The second law states that force is the product of the mass of an object and its acceleration. The third law states that every action has an equal and opposite reaction.
As per the second law, Force = mass x acceleration.
This can also be used to determine the "weight" of a body, which is nothing but the force with which a celestial body attracts the body. This attraction can be given in terms of the acceleration due to gravity, which has a value of 9.81 m/s^2 on Earth. Since mass is the quantity of matter contained in a body, it remains constant; however, the weight of the same body will vary from celestial body to celestial body. On Earth, the weight is the product of mass and g (= 9.81 m/s^2).
Hope this helps.