Transcript Newton`s Laws powerpoint

Force and Motion
Physical Science
Forces and Motion

Forces can create
changes in motion
(acceleration or
deceleration).
Definition of a Force
A
force is a
push or a pull.
Balanced Force

A force that
produces no
change in an
object’s motion
because it is
balanced by an
equal yet
opposite force.
Unbalanced Forces
Are forces that
result in an
object’s
motion being
changed.
+
Motion can be described
as:
A
change in an
object’s position.
Newton’s 1ST Law of
Motion

1st Laws States that an
object at rest will remain at
rest and an object in motion
will remain in motion,
unless an outside force acts
on it (such as friction). This
law is also called the LAW
OF INERTIA.

Ex. This law explains why
you fly forward in a car
when someone slams on
the brakes. Because of
Inertia, your body wants to
keep moving at the same
speed as the car.
Newton’s 2nd Law of
Motion

2nd Law States that a
force on an object will
move the object in the
direction of the force.
The relationship
between force, mass
and acceleration is
summarized by the
formula:
 f = ma

Ex. This law
explains why a golf
ball will roll in the
direction of a force
applied to it.
Q: The frog leaps from its resting position at the
lake’s bank onto a lily pad. If the frog has a mass
of 0.5 kg and the acceleration of the leap is 3 m/s2,
what is the force the frog exerts on the lake’s
bank when leaping?
(A) 0.2 N
(B) 0.8 N
(C) 1.5 N
(D) 6.0 N
Formula chart says F=ma, m is mass
in kg, a is acceleration in m/s2.
So, .5 kg x 3 m/s2= 1.5 N
Newton’s 3rd Law of
Motion
3rd Law States that
for every action
there is an equal but
opposite action.
 Ex. A skater pushes
back on the skates
but the skater moves
forward.


THESE LAWS EXPLAIN ALL MOTION
Q: The hands of a swimmer
pushing backward against
water represent an action
force. What is the reaction
force?
A. The swimmer’s body moving forward?
B. The water pushing against the swimmer’s hands
C. The swimmer’s body pushing against the water.
D. The water moving backward from the swimmer.
Friction
A force that opposes, or works
against, motion of two objects that
are touching.
Friction
•
•
Friction causes an
object to slow down
and stop.
Since the amount of
energy stays constant,
the energy becomes
heat.
Universal Law of Gravity
All objects in
the universe
attract each
other by the
force of
gravity.
Universal Law of
Gravity
Gravity varies depending
on two factors:
1) the mass of the object
doing the pulling, and
2) the distance from the center
of that object
On Earth gravity = 9.8 m/s/s
For
every
second that an
object falls its
speed increases
by 9.8 m/s