Newton’s Laws

Example Problem A plane fires a bullet with an initial velocity of 150 m/s at an angle of 37 0 below the horizontal. The bullet lands 3 seconds later. Find the components of the initial velocity. How far does the bullet travel in the horizontal direction before it lands? How high above the (level) ground was the plane when the bullet was fired? Find the magnitude of the velocity of the bullet right before it hits the ground.

Pretest #3 (“the crate in the snow”) v a

F by gravity F by snow

Pretest #3 (“the crate in the snow”) F by gravity F by snow ?

Motion (kinematics) Forces (dynamics) Causes 

Types of Forces Noncontact ForcesContact Forces PushesPulls Electromagnetic

Types of Forces Noncontact ForcesContact Forces Gravitational PushesPulls Electromagnetic

Types of Forces Noncontact ForcesContact Forces Gravitational PushesPulls W Electromagnetic

Types of Forces Noncontact ForcesContact Forces Gravitational PushesPulls ElectricMagnetic W Electromagnetic

Types of Forces Noncontact ForcesContact Forces Gravitational PushesPulls ElectricMagnetic W M Electromagnetic

Types of Forces Noncontact ForcesContact Forces GravitationalNuclear PushesPulls ElectricMagnetic W M Electromagnetic

Types of Forces Noncontact ForcesContact Forces GravitationalNuclear PushesPulls ElectricMagnetic Tension W M Electromagnetic

Types of Forces Noncontact ForcesContact Forces GravitationalNuclear PushesPulls ElectricMagnetic Tension W M T Electromagnetic

Types of Forces Noncontact ForcesContact Forces GravitationalNuclear PushesPulls ElectricMagnetic Normal Tension W M T Electromagnetic

Types of Forces Noncontact ForcesContact Forces GravitationalNuclear PushesPulls ElectricMagnetic Normal Tension W M T N Electromagnetic

Types of Forces Noncontact ForcesContact Forces GravitationalNuclear PushesPulls ElectricMagnetic Normal Tension W M T N perpendicular to surface Electromagnetic

Types of Forces Noncontact ForcesContact Forces GravitationalNuclear PushesPulls ElectricMagnetic FrictionNormal Tension W M T N perpendicular to surface Electromagnetic

Types of Forces Noncontact ForcesContact Forces GravitationalNuclear PushesPulls ElectricMagnetic FrictionNormal Tension W M T N f perpendicular to surface Electromagnetic

Aristotle B.C.

What is the velocity of this room? R E = 6 x 10 6 m v = 2  R E tt = 400 m/s

Galileo Galilei ( )

Ball on Ramp

a=0 An object at rest stays at rest and an object in motion stays in motion at constant speed in a straight line, unless acted upon by a net force.

Sir Isaac Newton ( )

Newton’s 1 st Law: No net force - no acceleration No acceleration = constant velocity An object at rest stays at rest and an object in motion stays in motion at constant speed in a straight line, unless acted upon by a net force.

Newton’s 2 nd Law: Deals with the effect of forces on an object.

Motion of the Block at rest uniform motion to the right moves to the right and speeds up without changing direction moves to the right, slows down and stops without changing direction VelocityAccelerationPush or Pull Necessary to Maintain Motion Dry Ice on Slate

Motion of the Block at rest uniform motion to the right moves to the right and speeds up without changing direction moves to the right, slows down and stops without changing direction VelocityAccelerationPush or Pull Necessary to Maintain Motion Dry Ice on Slate

Newton’s 2 nd Law: Net force causes acceleration (not velocity) The net force is the vector sum of all the individual forces on an object. W E,b N r,b F net W E,b a Acceleration is in same direction as the net force. a

Types of Forces Noncontact ForcesContact Forces GravitationalNuclear PushesPulls ElectricMagnetic FrictionNormal Tension W M T N f Electromagnetic Which one is the net force?

Pretest #3 (“the crate in the snow”) F by gravity F by snow ?

Pretest #3 (“the crate in the snow”) F by gravity F by snow