Transcript physics ch 7

Physics Chapter 7
Forces in
Two Dimensions
Equilibrium
State
of an object when the
net force is zero
Equilibrant
The
force that when applied
to a situation produces a state
of equilibrium
Equilibrium in 2 directions
 The
forces in both directions must
total zero to be in equilibrium.
SO…
 The forces in the x-direction must
total zero
 The forces is the y-direction must
total zero
REMEMBER
Normal
Force
Always
perpendicular to the
surface
Force
of Gravity
Always
earth
perpendicular to the


Force due
to gravity
Normal
Force
Projectile Motion
Motion
in the xdirection and the motion
in the y-direction are
independent of each
other.
X direction
Y direction
Notice how the
same point going
up reflects to a
corresponding
point going down.
V vert

v hor
Circular Motion

Uniform Circular Motion

The movement of an object or point mass at
constant speed around a circle with a fixed
radius.
v1
r1
Δr
r1
v2
r2
r2
Centripetal Acceleration

The acceleration of an object in uniform
circular motion always points in toward the
center of that circle.
v1
v2
a
r
v1
v2
Δv
v
r
a
v
t
t
Centripetal
Acceleration
v1
v2
a
v1
v2
r
Δv
r v r
v


r
v rt vt
 2r 


2
4 r
T 

ac 
 2
r
T
2
2
v
ac 
r
Newton’s 2nd Law
for Centripetal Acceleration
F  ma
mv
Fnet 
r
2
 4 r 
Fnet  m 2 
T


2
 Lever Arm
Length
of the rotation
 Torque
Product
of the force and the
lever arm