Newton’s Three Laws of Motion

Sir Isaac Newton

Mr. BoggioApril 2015

Newton’s Contributions to Science and Math

Calculus

Light is composed of a color spectrum

Reflecting Telescope

Laws of Motion

Theory of Gravitation

Newton’s First Law (Inertia)

Newton's first law of motion states that an object at rest remains at rest and an object in motion remains in motion with the same velocity unless acted upon by an unbalanced force

Balanced /Unbalanced Forces

Unequal opposing forces produce an unbalanced forcecausing 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 unbalanced force acting upon

them.

A book sliding across a table slows down and stops because of the force of friction.

If you throw a ball into the air it will eventually slow down and fall because of the force of gravity.

Four types of friction:• Sliding friction: ice skating• Rolling friction: bowling• Fluid friction (air or liquid): air or water resistance• Static friction: initial friction when moving an object

What is the unbalanced force that acts on an What is the unbalanced force that acts on an object in motion?object in motion?

Newton’s Second Law

Force equals mass times acceleration.

F = ma

Newton’s Second LawNewton’s Second Law

Force = Mass x AccelerationForce = Mass x AccelerationForce is measured in NewtonsForce is measured in Newtons

Acceleration of Gravity = 9.8 m/sAcceleration of Gravity = 9.8 m/s² (32 ft/s (32 ft/s²))Weight (force) = mass x gravityWeight (force) = mass x gravity

Moon’s gravity is 1/6 of the Earth’s

If you weigh 420 Newtons on earth, what will you weigh on the Moon?

Ans: 70 Newtons

If your mass is 41.5Kg on Earth what is your mass on the Moon?

Ans: ?

Falling Objects: Humans Terminal Velocity = 120 mph = 176 ft/sec

Acceleration Gravity = 9.8 m/sec² = 32 ft/sec²

F = ma = 68 kg (150 lbs.) x 9.8m/sec² = 668 Newtons

1 sec 32 ft/sec2 sec 64 ft/sec3 sec 96 ft/sec4 sec 128 ft/sec5 sec 160 ft/sec6 sec 176 ft/sec – Terminal Velocity

Terminal velocity is the highest velocity attainable by an object in free fall. It occurs once the sum of the drag force (friction) Fd and buoyancy equals the downward force of gravity FG acting on the object. Since the net force on the object is zero, the object has zero acceleration

Newton’s Third Law

For every action there is an equal and opposite reaction.

Newton’s 3rd Law

For every action there is an equal and opposite reaction.

Book toearth

Table onbook

Newton’s Third Law

Action: tire pushes on road

Reaction: road pushes on tire

reaction: rocket pushes on gases

action: gases push on rocket

Consider hitting a baseball with a bat. If we call the force applied to the ball by the bat the action force, identify the reaction force.

(a) the force applied to the bat by the hands

(b) the force applied to the bat by the ball

(c) the force the ball carries with it in flight

(d) the centrifugal force in the swing

ReviewNewton’s First Law:

Objects in motion tend to stay in motion and objects at rest tend to stay at rest unless acted upon by an unbalanced force.

Newton’s Second Law:

Force equals mass times acceleration (F = ma).2nd law applied to Gravity: Weight = mass x 9.8 m/s² or 32 ft/s²

Newton’s Third Law:

For every action there is an equal and opposite reaction.