Newton’s 1 st Law An object at rest tends to stay at rest and an object in motion tends to stay in motion unless acted upon by an unbalanced force.
Part 1: An Object at Rest Identify an object at rest Ex: chair on the floor, a plane on a runway These objects will not start moving until a is exerted on them. Ex: push or pull You tend to fall backward when your school bus starts to move.
Part 2: An Object in Motion An object moving at a certain velocity will continue to move at the same speed and in the same direction unless some acts on it. http://www.physicsclassroom.com/mmedia/newtlaws/il. cfm http://www.physicsclassroom.com/mmedia/newtlaws/il. cfm unbalanced force forever Ex: Riding in your car. When your mother or father comes to a stop then you would continue to move, however your seatbelt stops you.
Balanced Force Equal forces in opposite directions produce no motion
Unbalanced Force Unequal opposing forces produce an unbalanced force causing motion
If objects in motion tend to stay in motion, why don’t moving objects keep moving forever? Things don’t keep moving forever because there’s almost always an acting upon them. A book sliding across a table slows down and stops because of the force of If you throw a ball upwards it will eventually slow down and fall because of the force of unbalanced force gravity friction
Inertia The tendency of an object to resist a change in its motion Inertia can be described as the tendency of an object to keep doing whatever’s it’s doing.
Inertia Inertia is the reason objects at rest and objects in motion Inertia is the reason you slide toward the side of a car when the driver makes a sharp turn. remain at rest remain in motion
MASS and INERTIA The more an object has, the more the object has. Therefore an object with a small mass will have a inertia And an object with a large mass will have a inertia. Bigger objects are to start & stop MASSINERTIA HARDER Which vehicle has more inertia? SMALL LARGE
The truck is in motion. What is the force that causes it to stop? The car is at rest. What is the force that causes it to move? The push of the stopped car. The push of the truck.
Group Work! In your group take 3 MINUTES to come up with an example of Newton’s 1 st Law in everyday life. Be ready to explain using the proper vocabulary.
Assess Your Knowledge If gravity between the Sun and Earth suddenly vanished how would Earth move? Answer: In a straight path
To say that 1kg of matter weighs 10 N is to say that 1kg of matter Will weigh 10N everywhere Has less volume than 10kg of matter Has more inertia than 10kg of matter Is attracted to Earth with 10N of force Answer: D
If the net force on an object is zero then the object has Balanced forces Action forces Reaction forces Unbalanced forces Answer: A
The greater the mass of an object, The easier the object starts moving The more space the object takes up The greater its inertia The more balanced it is Answer: C