What is inertia white board marker hoop bottle

What is inertia? white board marker hoop bottle • An object’s resistance to changing its motion.

The amount of inertia possessed by an object is dependent solely upon its mass.

Mass—A Measure of Inertia • 2. 2 pounds near Earth’s surface.

Here is my first law. I called it NEWTON’S FIRST LAW

Deciphering Newton’s First Law “Every body persists in its state of being at rest or of moving uniformly straight forward, except insofar as it is compelled to change its state by force impressed. ” —Sir Isaac Newton Principia Mathematica (1687) Write: In your own words, what does this mean? Unless an unbalanced force acts on an object, Ø An object at rest stays at rest Ø An object in motion stays in motion Isaac Newton, 1642 -1727

Newton’s 1 st Law and You Wear seat belts!

C. NEWTON’S FIRST LAW is also known as THE LAW OF INERTIA

Here is my second law. I called it NEWTON’S SECOND LAW

Newton’s Second Law of Motion

Newton’s Second Law Part 1: The net force on an object causes its acceleration.

Net Force n Net Force, Total Force, Resultant Force Σ F = F 1 + F 2 + F 3 + … Fnet = F 1 + F 2 + F 3 + …

Mechanical Equilibrium n The resultant force is zero n All forces cancel out n There is no change in the objects motion

When net force is zero…

Car at Constant Speed ΣF = Normal Force = 2000 N Fa = 50 N Friction = 50 N Weight = 2000 N

Net Force Causes Acceleration • To increase the acceleration of an object, you must increase the net force acting on it. • An object’s acceleration is directly proportional to the net force acting on it: acceleration ~ net force (The symbol ~ stands for “proportional to. ”)

Newton’s Second Law Part 2: The mass of an object resists acceleration.

F C. Directly proportional o means… r increase the force A. if you applied c to the object the acceleration also increases. e A c c e l e r a t i o n

D. Inversely means… A c c e l e r a t i o n M A. if you increase the mass a of the object the acceleration does s the opposite it decreases. s

Mass Resists Acceleration • The same force applied to twice as much mass results in only half the acceleration. • The acceleration is inversely proportional to the mass.

Newton’s Second Law. Net Force causes acceleration, mass resists it. a = Fnet m or Fnet = ma

2 nd Law • When mass is in kilograms and acceleration is in m/s/s, the unit of force is in Newtons (N). • One newton is equal to the force required to accelerate one kilogram of mass at one meter/second.

Force is measured in Newtons; 2 (1. 00 kg)(1. 00 m/s )= 1 N (Newton)

Check Your Understanding • 1. What acceleration will result when a 12 N net force applied to a 3 kg object? A 6 kg object? • 2. A net force of 16 N causes a mass to accelerate at a rate of 5 m/s 2. Determine the mass. • 3. How much force is needed to accelerate a 66 kg skier 1 m/sec? • 4. What is the force on a 1000 kg elevator that is falling freely at 9. 8 m/sec?

Check Your Understanding • 1. What acceleration will result when a 12 N net force applied to a 3 kg object? 12 N = 3 kg x 4 m/s/s • 2. A net force of 16 N causes a mass to accelerate at a rate of 5 m/s 2. Determine the mass. 16 N = 3. 2 kg x 5 m/s/s • 3. How much force is needed to accelerate a 66 kg skier 1 m/sec? 66 kg-m/sec or 66 N • 4. What is the force on a 1000 kg elevator that is falling freely at 9. 8 m/sec? 9800 kg-m/sec or 9800 N