newton´s laws of motion.pptx

7/30/2019 NEWTONS LAWS OF MOTION.pptx

1/20

By: Mikayla van den brenk

Paula Castellanos

*


2/20

*

*Describe Newtons first law of motion, and

explain how it relates to objects at rest

and objects in motion

*State Newtons second law of motion, and

explain the relationship between force,

mass, and acceleration

*State Newtons third law of motion, and

give examples of force pairs


3/20

*

*Newtons first law of motion describes the

motion of an object that has a net force of 0 N

acting on it. This law may seem complicatedwhen you first read it. But, it is easy to

understand when you consider its two parts

separately.


4/20

*

*An object that is not moving is said to be at

rest. A chair on the floor and a golf ball

balanced on a tee are examples of objects atrest. Newtons first law says that objects at

rest will stay at rest unless they are acted on

by an unbalanced force.


5/20

*For example, objects will not start moving

until a push or a pull is exerted on them. So, a

chair wont slide across the room unless youpush the chair. And, a golf ball wont move off

the tee unless the ball is struck by a golf club.


6/20

*

*The second part of Newtons first law is about

objects moving with a certain velocity. Such

objects will continue to move forever with thesame velocity unless an unbalanced force acts

on them


7/20

*

*An object in motion will stay in motion forever

unless it is acted on by an unbalanced force.

So, you should be able to give your desk a pushand send it sliding across the floor. If you push

your desk, the desk quickly stops. Why?


8/20

There must be an unbalanced force that acts on

the desk to stop its motion. That unbalanced

force is friction. The friction between the deskand the floor works against the motion of the

desk


9/20

*

*Inertia is the tendency of all objects to resist

any change in motion. Because of inertia, an

object at rest will remain at rest until a forcemakes it move. Likewise, inertia is the reason

a moving object stays in motion with the same

velocity unless a force changes its speed or

direction.


10/20

*

*Mass is a measure of inertia. An object that has

a small mass has less inertia than an object

that has a large mass. So, changing the motionof an object that has a small mass is easier

than changing the motion of an object that has

a large mass.


11/20

*

*Newtons second law describes the motion of

an object when an unbalanced force acts on

the object. As with Newtons first law, youshould consider the second law in two parts.


12/20

*

*Suppose you are pushing an empty cart. You

have to exert only a small force on the cart to

accelerate it. But, the same amount of forcewill not accelerate the full cart as much as the

empty cart.


13/20

*

*The cart will start moving faster than if you

gave it only a soft push. So, an objects

acceleration increases as the force on theobject increases. On the other hand, an

objects acceleration decreases as the force on

the object decreases. The acceleration of an

object is always in the same direction as the

force applied.


14/20


15/20

*

*Newtons second law explains

why objects fall to Earth with

the same acceleration. You cansee how the large force of

gravity on the watermelon is

offset by its large mass. Thus,

you find that the accelerations

of the watermelon and theapple are the same when you

solve for acceleration.


16/20

*

*Newtons third law can be simply stated as

follows: All forces act in pairs. If a force is

exerted, another force occurs that is equal insize and opposite in direction. The law itself

addresses only forces. But the way that force

pairs interact affects the motion of objects.

*


17/20

*How do forces act in pairs? Study the

picture to learn how one force pair

helps propel a swimmer through

water. Action and reaction forcepairs are present even when there is

no motion.


18/20

*

*Newtons third law says

that all forces act in pairs.

When a force is exerted,

there is always a reaction

force. A force never acts by

itself.


19/20

*

*Gravity is a force ofattraction between objects

that is due to their masses.If you drop a ball, gravitypulls the ball toward Earth.This force is the action forceexerted by Earth on the ball.But gravity also pulls Earthtoward the ball. The force isthe reaction force exertedby the ball on Earth.

*


20/20

*

*http://my.hrw.com/tabnav/controller.jsp?isbn=

0030462495
http://my.hrw.com/tabnav/controller.jsp?isbn=0030462495http://my.hrw.com/tabnav/controller.jsp?isbn=0030462495http://my.hrw.com/tabnav/controller.jsp?isbn=0030462495http://my.hrw.com/tabnav/controller.jsp?isbn=0030462495http://my.hrw.com/tabnav/controller.jsp?isbn=0030462495

newton´s laws of motion.pptx

Documents