2.  Issac Newton was born in 1643 in England. He was a physicist and mathematician. Newton contributed many things to science, but he is best known for his work, the ‘Philosophiae Naturalis Principia Mathematica’ (‘Mathematical Principles of Natural Philosophy’). It was in this work that he showed how a universal force, gravity, applied to all parts of the universe. He is known as the greatest scientist of his era. He passed away in 1727.

3.  An object at rest stays at rest and an object in motion stays in motion in with the same speed and in the same direction unless acted upon by an unbalanced force.

4.  Force: A push or a pull  Balanced forces: forces on an object that are equal in size and opposite in direction. They do not cause a change in motion.  Unbalanced forces: Always cause a change in motion. They are not equal and opposite.  Inertia: The natural tendency of objects to resist changes in their state of motion.