is the difference between two opposing forces. Newton’s 2nd Law of Motion states that if a net force acts on an object, the object will in the direction of the force. Acceleration is a change in . It can either be or . Mass is the amount of matter contained in an object. Mass does not change with changes in . The acceleration of any object falling to the surface of the Earth is . This means that at the first second, the object will be falling with a speed of 9.8. m/s2. At 2 seconds, the object will be falling at the rate of ; at 3 seconds, it will be falling at the rate of , and so on.