Newton’s Laws and Motion

3 Laws of Motion 1 st Law – An object at rest will stay at rest, and an object in motion will stay in motion at constant velocity, unless acted upon by an unbalanced force. 1 st Law – An object at rest will stay at rest, and an object in motion will stay in motion at constant velocity, unless acted upon by an unbalanced force. 2 nd Law – Force equals mass times acceleration. 2 nd Law – Force equals mass times acceleration. 3 rd Law – For every action there is an equal and opposite reaction. 3 rd Law – For every action there is an equal and opposite reaction.

4 Types of Friction There are four main types of friction: There are four main types of friction: –Sliding friction: –Sliding friction: ice skating –Rolling friction: –Rolling friction: bowling –Fluid friction (air or liquid): –Fluid friction (air or liquid): air or water resistance –Static friction: –Static friction: initial friction when moving an object

2 nd Law Formula How much force is needed to accelerate a 1400 kilogram car 2 meters per second/per second? 1. Write the formula F = m x a 2. Fill in given numbers F = 1400 x 2 3. Solve for the unknown 2800 N

2 nd Law Practice 1. What acceleration will result when a 12 N net force is applied to a 3 kg object? A 6 kg object? 1. What acceleration will result when a 12 N net force is 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. 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/sec? 3. How much force is needed to accelerate a 66 kg skier 1 m/sec/sec? 4. What is the force on a 1000 kg elevator that is falling freely at 9.8 m/sec/sec? 4. What is the force on a 1000 kg elevator that is falling freely at 9.8 m/sec/sec?

2 nd Law Practice Answers 1. What acceleration will result when a 12 N net force applied to a 3 kg object? 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 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. 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 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/sec? 3. How much force is needed to accelerate a 66 kg skier 1 m/sec/sec? 66 kg-m/sec/sec or 66 N 4. What is the force on a 1000 kg elevator that is falling freely at 9.8 m/sec/sec? 4. What is the force on a 1000 kg elevator that is falling freely at 9.8 m/sec/sec? 9800 kg-m/sec/sec or 9800 N 9800 kg-m/sec/sec or 9800 N

ALL NOTES TO THIS POINT ARE FOR THE QUIZ ALL NOTES TO THIS POINT ARE FOR THE QUIZ PRINT REMAINING NOTES AS SLIDES AS A HANDOUT TO TEACH FOR THE TEST PRINT REMAINING NOTES AS SLIDES AS A HANDOUT TO TEACH FOR THE TEST

Air resistance- fluid friction acting on an object moving through air Air resistance- fluid friction acting on an object moving through air Acceleration- rate at which an object’s velocity changes Acceleration- rate at which an object’s velocity changes Gravity- force that exists between any two objects that have mass, attracting or pulling them together Gravity- force that exists between any two objects that have mass, attracting or pulling them together

Friction- force that opposes motion, or resistance, caused when two surfaces touch or rub together Friction- force that opposes motion, or resistance, caused when two surfaces touch or rub together Speed- rate at which the position of an object changes Speed- rate at which the position of an object changes Inertia- tendency of a still or moving object to resist a change in its motion Inertia- tendency of a still or moving object to resist a change in its motion Kinetic energy- energy an object has due to its motion Kinetic energy- energy an object has due to its motion

Velocity- rate at which an object moves in a certain direction Velocity- rate at which an object moves in a certain direction Mass- amount of matter in an object Mass- amount of matter in an object Force- push or pull that acts on an object, causing it to move, change speed or direction, or to stop moving Force- push or pull that acts on an object, causing it to move, change speed or direction, or to stop moving Momentum- property of matter due to its mass and velocity Momentum- property of matter due to its mass and velocity

Weight- measure of the force of gravity acting on an object Weight- measure of the force of gravity acting on an object Potential energy- energy that is stored, available as a result of an object’s position or condition Potential energy- energy that is stored, available as a result of an object’s position or condition Newton- unit of force Newton- unit of force

Motion- the process of changing from one position, or place, to another. Motion- the process of changing from one position, or place, to another. Displacement- describes both how far an object moved from its original position and in what direction it moved. Displacement- describes both how far an object moved from its original position and in what direction it moved.

Example of displacement: Example of displacement: A runner follows a path through a park and goes 3 kilometers north, turns right, and travels 4 kilometers east. The total distance traveled is 7 kilometers, but her final position is only 5 kilometers northeast of her starting point. So her displacement is 5 kilometers northeast. A runner follows a path through a park and goes 3 kilometers north, turns right, and travels 4 kilometers east. The total distance traveled is 7 kilometers, but her final position is only 5 kilometers northeast of her starting point. So her displacement is 5 kilometers northeast.

Law of conservation of momentum: Law of conservation of momentum: –momentum= mass x velocity –Momentum of an object does not change unless its mass changes, its velocity changes, or both change –If there is no outside force acting, momentum will not change

Free fall- when gravity alone is acting on an object Free fall- when gravity alone is acting on an object –Astronauts experience this in their aircraft

Finding speed Finding speed –Speed = distance / time –Example: A cruise ship travels 1,000 km in 25 hours. Their average speed is 1000/25= 40 km per hour

Net force- the force that results from all the combined forces acting on an object Balanced force- forces that completely cancel each other out Example- You are holding a piece of pizza. The force of gravity pulling it down is equal to the amount of force your hand is providing to hold it up.

Unbalanced force-when forces act on each other and do not cancel out Example- The game of tug of war. When one team pulls harder, the force is unbalanced and the opposing team starts to move.

Displacement example A robot went 20 feet south, 20 feet west, and 20 feet north.

Average Speed Example Mr. Robot travels 500 feet in 2 minutes. What is his average speed?