WHAT IS INERTIA? Newton’s Laws Standard Summarize And illustrate the concept of inertia.

Newton’s First Law of Motion (“the law of inertia”) An object at rest will remain at rest unless acted on by an unbalanced force. An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

WHAT IS INERTIA? The tendency of an object to resist change in its motion. Whether an object is moving or at rest, every object resists any change to its motion. Examples: **Air hockey puck will ride on air once you push it ** Tennis ball flies through the air once you hit it with a racket In both of these cases, the object continues to move even after you remove the force.

Inertia explains common events like: When you are in a car and stop suddenly, you will continue to move forward. (WHY YOU NEED TO WEAR SEAT BELTS!!) Passengers in a moving car have inertia. Therefore a force is required to change their motion. That force is exerted by the safety belt. If the safety belt is not worn, that force is exerted by the windshield instead.

What is more difficult to move? A 1 quart jar of pennies or a 1 quart jar of feathers? Obviously the pennies…. Why? Obviously the pennies…. Why? What is the difference between a quart of pennies and a quart of feathers? What is the difference between a quart of pennies and a quart of feathers? Both jars occupy the same amount of space and have the same amount of volume. Both jars occupy the same amount of space and have the same amount of volume.

The difference is the amount of MASS. What is Mass? Mass is the amount of matter in an object. The amount of inertia an object has depends on how much mass it has. The greater the mass of an object, the greater its inertia!! Mass can also be defined as a measure of the inertia of an object.

Newton’s 2 nd Law of Motion The net force on an object is equal to the product of it’s acceleration and mass. Force = Mass x Acceleration –Remember, the unit of force is a Newton. Acceleration is the rate at which velocity changes.

Newton’s Second Law of Motion Acceleration will increase when you increase the FORCE on the object. Acceleration will increase when you decrease the MASS of an object.

Examples: You are pulling a wagon with two dogs in the back. If one dog jumps out, will the acceleration increase or decrease? Suppose you know the acceleration of a shopping cart as it rolls down a super market isle. You want to find the force with which it was pushed. What other information do you need in order to find the force?

Newton’s Third Law of Motion Newton’s third law states that if one object exerts a force on another object, then the second object exerts a force of equal strength in the opposite direction on the first object. In other words, every action has an equal, but opposite reaction.

Newton’s Third Law of Motion A squid applies Newton’s third law of motion to move itself through the water. –When a squid pushes water out, the expelled water pushes back and forces the squid to move ahead. Water pushed out is the action. Squid being propelled forward is the reaction.

Newton’s Third Law of Motion When a rocket lifts off from the ground. –The force of the air pushing out of the rocket towards the ground propels the rocket in the opposite direction Reaction Force Action Force ROCKETROCKET