Physical SciencePhysical Science10111011

Chapter 2Chapter 2

Newton’s Laws of Newton’s Laws of MotionMotion

2.1 Newton’s First Law of 2.1 Newton’s First Law of MotionMotion

Every object continues in a state Every object continues in a state of rest, or in a state of motion in of rest, or in a state of motion in a straight line, at contanst speed, a straight line, at contanst speed, unless it is compelled to change unless it is compelled to change that state by forces exerted upon that state by forces exerted upon it.it.

Usually called the Law of Usually called the Law of InertiaInertia Essentially the same as Galileo’s Essentially the same as Galileo’s

ideaidea

2.2 Newton’s Second Law of 2.2 Newton’s Second Law of MotionMotion

The acceleration produced by a net The acceleration produced by a net force on an object is directly force on an object is directly proportional to the net force, is in proportional to the net force, is in the same direction as the net the same direction as the net force, and is inversely proportional force, and is inversely proportional to the mass of the object.to the mass of the object.

Acceleration =

Net Force

Mass

2.2 Newton’s Second Law of 2.2 Newton’s Second Law of MotionMotion

a = Fm

2.2 Newton’s Second Law of 2.2 Newton’s Second Law of MotionMotion

2.2 Newton’s Second Law of 2.2 Newton’s Second Law of MotionMotion

2.2 Newton’s Second Law of 2.2 Newton’s Second Law of MotionMotion

Acceleration Due to GravityAcceleration Due to Gravity An object in free fall accelerates toward An object in free fall accelerates toward

the Earth at 10 m/sthe Earth at 10 m/s22 (if we neglect air (if we neglect air

resistance).resistance). We assign the letter g to acceleration We assign the letter g to acceleration

due to gravity.due to gravity.

g = Wm W =

mg

2.2 Newton’s Second Law of 2.2 Newton’s Second Law of MotionMotion

Acceleration Due to GravityAcceleration Due to Gravity Objects of differing masses will Objects of differing masses will

accelerate toward the Earth at the accelerate toward the Earth at the same rate (if air resistance is same rate (if air resistance is neglected).neglected).

This has been proven during an This has been proven during an Apollo Mission to the Moon. A Apollo Mission to the Moon. A hammer and a feather were released hammer and a feather were released at the same time. Both struck the at the same time. Both struck the ground at the same time.ground at the same time.

2.2 Newton’s Second Law of 2.2 Newton’s Second Law of MotionMotion

Acceleration Due to GravityAcceleration Due to Gravity A skydiver accelerates toward the ground. A skydiver accelerates toward the ground. As he does, air resistance increases to the As he does, air resistance increases to the

point where it equals his weight.point where it equals his weight. The skydiver then stops accelerating and The skydiver then stops accelerating and

falls at a constant rate called Terminal falls at a constant rate called Terminal Velocity of approximately 200 km/h (125 Velocity of approximately 200 km/h (125 mi/h).mi/h).

2.2 Newton’s Second Law of 2.2 Newton’s Second Law of MotionMotion

Acceleration Due to GravityAcceleration Due to Gravity By opening his parachute, the By opening his parachute, the

skydiver increases the total force of skydiver increases the total force of air resistance, slowing him down to a air resistance, slowing him down to a speed that allows him to land without speed that allows him to land without injury. (22 km/h or 14 mi/h)injury. (22 km/h or 14 mi/h)

2.3 Forces and 2.3 Forces and InteractionsInteractions

When you push on a wall, the When you push on a wall, the wall pushes back.wall pushes back.

2.4 Newton’s Third Law of 2.4 Newton’s Third Law of MotionMotion

Whenever one object exerts a Whenever one object exerts a force on a second object, the force on a second object, the second object exerts an equal second object exerts an equal and opposite force on the first.and opposite force on the first.

For every action, there is an For every action, there is an equal and opposite reaction.equal and opposite reaction.

2.4 Newton’s Third Law of 2.4 Newton’s Third Law of MotionMotion

2.4 Newton’s Third Law of 2.4 Newton’s Third Law of MotionMotion

2.4 Newton’s Third Law of 2.4 Newton’s Third Law of MotionMotion

2.5 Vectors and Scalars2.5 Vectors and Scalars

Scalars have sizeScalars have size Mass, speed, volume, Mass, speed, volume,

temperaturetemperature Vectors have size and Vectors have size and

directiondirection Velocity, acceleration, Velocity, acceleration,

forceforce

2.5 Vectors and Scalars2.5 Vectors and ScalarsAdding VectorsAdding Vectors

2.5 Vectors and Scalars2.5 Vectors and ScalarsAdding VectorsAdding Vectors

2.5 Vectors and Scalars2.5 Vectors and ScalarsAdding VectorsAdding Vectors

2.5 Vectors and Scalars2.5 Vectors and ScalarsAdding VectorsAdding Vectors

Example of Velocity Example of Velocity VectorsVectors

Components of VectorsComponents of Vectors

Components of VectorsComponents of Vectors