1. Newton’s Laws

2. Sir Isaac Newton British Scientist.
Discovered/explained how gravity works.
Knew that unbalanced forces were needed to change the motion of objects.
Reasoned that an unbalanced force kept the moon moving around the Earth.

3. Sir Isaac Newton
5. Newton summarized his ideas in the law of universal gravitation.
6. The law describes the relationship between gravitational force, mass, and distance.
7. The law applies to every object in the universe.

4. The Law of Universal Gravitation
All objects in the universe attract each other through gravitational force.
The magnitude of the force depends upon mass and distance.
The greater the mass, the greater the force of gravity and attraction.

5. Newton’s First Law
An object at rest remains at rest, and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force.

6. Newton’s First Law
Objects at rest will not move until a push or a pull is exerted on them.
Objects already in motion will remain at a constant velocity until an unbalanced force acts upon them.
Friction acts as an unbalanced force in many situations.

7. Newton’s First Law
4. Inertia: the tendency of an object to resist any change in motion.
5. Mass is tied to inertia.
6. The greater the mass, the greater the inertia.
7. The lesser the mass, the lesser the inertia.

8. Newton’s First Law

9. Newton’s Second Law
The acceleration of an object depends on the mass of the object and the amount of force applied.

10. Newton’s Second Law
Describes the motion of an object after an unbalanced force has acted.
Acceleration increases as mass decreases.
Acceleration decreases as mass increases.
An object accelerates in the same direction as the force being applied.

11. Newton’s Second Law
5. To increase acceleration, an increase in force is needed.
6. An object’s acceleration will decrease as the force on the object decreases.

12. Newton’s Third Law
Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first.

13. Newton’s Third Law All forces act in pairs.
The way force pairs interact, changes motion.
Action and then reaction.
Action and reaction pairs act on different objects.
The forces are equal in size but opposite in direction.

14. Newton’s Third Law 6. A force never acts by itself.
7. Gravity is also a reactionary force.
8. Gravity will not only pull an object toward the Earth, but also pull the Earth toward the object.