Transcript Newton`s 1st Law

Newton’s Laws
Example Problem
A plane fires a bullet with an initial velocity of
150 m/s at an angle of 370 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”)
a
v
Pretest #3
(“the crate in the snow”)
Fby snow
Fby
Pretest #3
(“the crate in the snow”)
Fby snow
Fby
?
Forces
(dynamics)
D Motion
(kinematics)
Types of Forces
Noncontact Forces
Electromagnetic
Contact Forces
Pushes
Pulls
Types of Forces
Noncontact Forces
Gravitational
Electromagnetic
Contact Forces
Pushes
Pulls
Types of Forces
Noncontact Forces
Gravitational
W
Electromagnetic
Contact Forces
Pushes
Pulls
Types of Forces
Noncontact Forces
Gravitational
Electromagnetic
W
Electric
Magnetic
Contact Forces
Pushes
Pulls
Types of Forces
Noncontact Forces
Gravitational
Electromagnetic
Pushes
W
Electric
Contact Forces
Magnetic
M
Pulls
Types of Forces
Noncontact Forces
Gravitational
Electromagnetic
Nuclear
W
Electric
Contact Forces
Magnetic
M
Pushes
Pulls
Types of Forces
Noncontact Forces
Gravitational
Electromagnetic
Contact Forces
Nuclear
Pushes
Pulls
W
Tension
Electric
Magnetic
M
Types of Forces
Noncontact Forces
Gravitational
Electromagnetic
Contact Forces
Nuclear
Pushes
Pulls
W
Tension
Electric
Magnetic
M
T
Types of Forces
Noncontact Forces
Gravitational
Electromagnetic
Contact Forces
Nuclear
Pushes
Pulls
W
Tension
Electric
Magnetic
M
Normal
T
Types of Forces
Noncontact Forces
Gravitational
Electromagnetic
Contact Forces
Nuclear
Pushes
Pulls
W
Tension
Electric
Magnetic
M
Normal
N
T
Types of Forces
Noncontact Forces
Gravitational
Electromagnetic
Contact Forces
Nuclear
Pushes
Pulls
W
Tension
Electric
Magnetic
M
Normal
N
perpendicular to
surface
T
Types of Forces
Noncontact Forces
Gravitational
Electromagnetic
Contact Forces
Nuclear
Pushes
Pulls
W
Tension
Electric
Magnetic
M
Friction
Normal
N
perpendicular to
surface
T
Types of Forces
Noncontact Forces
Gravitational
Electromagnetic
Contact Forces
Nuclear
Pushes
Pulls
W
Tension
Electric
Magnetic
Friction
M
f
Normal
N
perpendicular to
surface
T
Aristotle
384 - 322 B.C.
What is the velocity of this
room?
v=
2  RE
Dt
= 400 m/s
RE = 6 x 106 m
Galileo Galilei (1564-1642)
Ball on Ramp
Ball on Ramp
Ball on Ramp
Ball on Ramp
Ball on Ramp
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.
a=0
Sir Isaac
Newton
(1642-1727)
Newton’s 1st 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 2nd Law:

Deals with the effect of forces on an
object.
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
Velocity Acceleration Push or Pull Necessary
to Maintain Motion
0
0
0
0
0
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
Velocity Acceleration Push or Pull Necessary
to Maintain Motion
0
0
0
0
0
Newton’s 2nd Law:


Net force causes acceleration (not velocity)
The net force is the vector sum of all the individual
forces on an object.
Nr,b
Fnet
a
WE,b
WE,b
Nr,b
Acceleration is in same direction as the net force.
a
Which one is the net force?
Types of Forces
Noncontact Forces
Gravitational
Electromagnetic
Contact Forces
Nuclear
Pushes
Pulls
W
Tension
Electric
Magnetic
Friction
M
f
Normal
N
T
Pretest #3
(“the crate in the snow”)
Fby snow
Fby
?
Pretest #3
(“the crate in the snow”)
Fby snow
Fby