with it.
the force.
e.
or slides on a plane surface, it usually simplifies the solution to take the axes in the directions parallel and perpendicular to this surface, even
en replaced by its components, so you don't count it twice.
al to zero.
w
to relate the forces they exert on each other.
e target variables.
Chapter 5: Applying Newton’s Laws
5.1 Using Newton's First Law: Particles in Equilibrium
Equilibrium
– a body at rest or moving with constant velocity in an inertial frame of reference
•
Ex. A hanging lamp, a suspension bridge, an airplane flying straight and level at a constant
speed
Newton’s First Law:
When a particle is at rest or is moving with constant velocity in an inertial frame of
reference, the net force acting on it—that is, the vector sum of all the forces acting on it—must be zero
•
We most often use this equation in component form:
=
Fx
0
=
Fy
0
1.
5.2 Using Newton's Second Law: Dynamics of Particles
Dynamics
– the study of the causes of motion and changes in motion
=
Fx
max
=
Fy
may
Apparent Weight and Apparent Weightlessness
When a passenger with mass
m
rides in an elevator with yacceleration
ay
,
a scale shows the
passenger's apparent weight to be
=
( +
)
n
m g ay
•
When the elevator is accelerating upward,
ay
is positive and
n
is greater than the
passenger's weight
=
w
mg
•
When the elevator is accelerating downward,
ay
is negative and
n
is less than the
weight
•
The extreme case occurs when the elevator has a downward acceleration
= 
ay
g
,
that
is, when it is in free fall. In that case,
n
= 0 and the passenger
seems
to be weightless.
o
An astronaut orbiting the earth in a spacecraft experiences
apparent
weightlessness
o
In each case, the person is not truly weightless because there is still a
gravitational force acting
5.3 Frictional Forces
Contact forces
– a force between two objects (or an object and a surface) that are in direct contact with each
other
•
The normal force is one example of a contact force
•
Friction:
Page  1
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
o
This is the end of the preview.
Sign up
to
access the rest of the document.
 Spring '11
 McDemus
 Physics, Circular Motion, Force, Inertia, Normal Force

Click to edit the document details