Newton’s Laws of Motion Chapter 4 Sections 1, 2, and 3 Glencoe: Pages 98-117.

Newton’s Laws of Motion Chapter 4 Sections 1, 2, and 3

Glencoe: Pages 98-117

Newton’s 1st Law

• An object at rest will remain at rest, and an object in motion will remain in motion unless acted on by an outside force

• Inertia – the tendency of an object to continue its current state of motion, at rest or motion

Example: pulling a tablecloth out

from under the table setting, or a car running into a wall

Newton’s 1st Law• If the car were to abruptly stop and the seat belts were not being worn, then the passengers in motion would continue in motion. The passengers would likely be propelled from the car and be hurled into the air becomes projectiles and continue in projectile-like motion.

Newton’s 1st Law• In this example, the ladder continues in motion because no outside force changes its original motion, until the ladder hits the ground.

Newton’s 2nd Law

• The unbalanced force acting on an object equals the object’s mass times the object’s acceleration

F = m•a• SI units for force = Newton

***(1 N = 1 kg·m/s2)***

Newton’s 2nd Law

It is obviously takes less force to make the ball accelerate because the ball has less mass.

Newton’s 2nd Law

• Example: Think of the force required to push an empty shopping cart, and the force required to push a full shopping cart. What is the difference?

• More force applied = greater acceleration

Newton’s 2nd Law

•Weight ≠ Mass

Weight – the measure of gravity pulling on an object

Mass – the measure of the amount of matter in an object

Newton’s 2nd LawWeight influences shape

On land a supporting skeleton is required

In water less body support required because the water helps lift the mass

*Animals can be larger if they live in the water

Newton’s 2nd Law

•Free fall – motion of a body when the only force acting on it is gravity•Terminal velocity – maximum velocity reached when air resistance pushes up as much as gravity pulls down

Force of gravity pulling down = force of air resistance pushing up

Newton’s 3rd Law•For every action there is an equal but opposite reaction

***Action and reaction forces are applied to different objects

These forces occur in pairs at the same time, but do not cancel out!

Example: rocketry

Newton’s 3rd Law

Actions and Reactions