Newton's Laws Notes (Student Copy) PDF

Newton’s Laws of Motion A force is a push or pull. Sir Isaac Newton was a mathematician and scientist who published his observations and theories about force and motion in 1687. The three “laws” he presented are still the foundation of modern physics !  Newton’s FIRST Law of Motio...

Newton’s Laws of Motion A force is a push or pull. Sir Isaac Newton was a mathematician and scientist who published his observations and theories about force and motion in 1687. The three “laws” he presented are still the foundation of modern physics !  Newton’s FIRST Law of Motion ○ An object at rest stays at rest and an object in motion stays in motion with the same speed and same direction unless acted upon by an unbalanced force. ○ Also known as the ‘Law of Inertia’ Wait - what is an unbalanced force? And…this weird Inertia word?  Newton’s FIRST Law of Motion (continued) ○ Unbalanced force - outside force acting on an object causing the object to accelerate or change its motion ○ Inertia - the tendency of an object to resist For example: objects (including you) resist changes in their motion. When a car is going 80 km/hr is stopped by a brick wall, your body keeps moving at 80 km/hr. This is why it’s important to wear seatbelts! Newton’s FIRST Law of Motion [EXAMPLE] Newton’s FIRST Law of Motion [VIDEO]  Newton’s SECOND Law of Motion ○ The acceleration of an object increases with increased force, decreases with increased mass, and is in the same direction as the force.  Newton’s SECOND Law of Motion (continued) ○ The net force of an object is equal to the product of its mass and acceleration Force = mass x acceleration ○ Force is measured in Newtons (N) ○ Gravity is measured as how fast objects accelerate towards each other the average gravitational pull of the Earth is 9.8 m/s2  Yes, another formula - so let’s practice! Force = mass x acceleration F=m✖a How much force is needed to accelerate a 1,400 kg car 2 m/s/s? m = 1,400 kg a = 2 m/s/s F = 1,400 ✖ 2 = 2,800 Newtons  So what does the 2nd law mean? ○ Force is DIRECTLY proportional to acceleration The greater the force, the greater the acceleration The smaller the force, the smaller the acceleration ○ Mass is OPPOSITELY proportional to acceleration The greater the mass, the smaller the acceleration The smaller the mass, the greater the acceleration Newton’s SECOND Law of Motion [EXAMPLE] Newton’s SECOND Law of Motion [VIDEO]  Newton’s THIRD Law of Motion ○ When one object exerts a force on another object, the second object exerts an equal and opposite force on the first object. ○ In other words, for every action there is an equal and opposite reaction. ○ Action - Reaction forces Newton’s THIRD Law of Motion [EXAMPLE] Newton’s THIRD Law of Motion [MORE EXAMPLES] ○ When you sit in your chair, your body exerts a downward force on the chair and the chair exerts an upward force on your body. ○ Birds depend on Newton’s third law of motion. As the birds push down on the air with their wings, the air pushes their wings up and gives them lift. Newton’s THIRD Law of Motion [VIDEO]