Newtons first law states that an object in motion will remain in motion unless acted upon by an unbalanced force. This force could be anything from friction to wind resistance. Without these unbalanced forces any object would remain at a constant velocity if a force was applied.
Isaac Newton’s second law of motion states that the greater the mass the greater amount of force needed to accelerate the object. Acceleration happens when a force is applied to an object. We use this law everyday without knowing it. For example if I push a ten pound medicine ball it requires a greater force than pushing a marble. The mathematic equation for this law is force equals mass times acceleration.
Newton’s third law of motion is for every action there is an equal and opposite reaction. This means when there is a force applied there is an opposing force equally as strong. So when you push any object that object pushes back. This is Newton’s third law of motion.
Newton discovered gravity when he saw an apple fall from a tree. According to his second law there had to be a force to make the apple go down. He decided to call this gravity. Then he thought what if the apple tree was twice as tall? Then gravity would reach up there too. That is how Sir Isaac newton discovered gravity.
So in conclusion Newton created the laws of motion and discovered gravity. These were very important to the advancement of physics. However these were just a few of his many contributions.