Transcript Force and Newton*s Laws Flash Notes

Force and
Newton’s Laws
Pushing and Pulling
Essential Questions
 What
relationships exists among force,
mass, speed, and acceleration?
 What
evidence indicates a force has
acted on a system? Is it possible for a
force to act on a system without having
an effect?
Force
 Force:
A push or a pull in a direction.
Force is measured in Newtons (N)
Common Forces
 Friction:
a contact force between two
objects sliding together.
 Air Resistance: Friction between air and
objects.
 Gravity: A non-contact attraction force
between objects that have mass.


Larger mass = larger gravity
Smaller distance = larger gravity
Forces
 Balanced
Forces: Two or more equal
forces acting on an object. Object is
either not moving or traveling at a
constant velocity.
Forces
 Unbalanced
Forces: Two or more unequal
forces acting on an object. Unbalanced
forces change the speed or direction of
an object (velocity).
Newton’s Laws of Motion
 Law
1: If the total force acting on an
object is zero the objects motion does not
change.
(-)50N
50N
Newton’s Law of Motion
 Law
2: Acceleration = Force / mass
Force = (Mass)(Acceleration)
Mass = Force / Acceleration
Newton’s Law of Motion
 Law
3: For every action there is an equal
and opposite reaction.
 http://www.youtube.com/watch?v=UARB
HORBhC8&feature=related
Free body Diagrams
A
free body diagram shows the forces
acting on an object.
Example 1

A student in a random middle school science
class angers his teacher and is suspended
from the ceiling by his toe nails. He remains
there for two days until his nails fall out and he
crashes to the floor.
What forces are
acting on the
student?
Rope
(tension)
Gravity
Example 2
 Police
are chasing a student who stole
their teacher’s bicycle. The forces are
labeled with arrows, but you must give
them names. What does each arrow
represent?
Normal Force
Air Resistance
Biker/Student
Gravity