Download Forces in Two Dimensions Section 7.1

Forces in Two Dimensions
Section 7.1
Physics
Objectives
• Determine the force that produces
equilibrium when three forces act on an
object.
• Analyze the motion of an object on an
inclined plane with and without friction.
How have we looked at forces in
two dimensions?
• Friction acting on a crate sliding on the
ground.
• What angle are these two forces in relation
to each other?
– 90°
– We will now examine forces at other angles to
each other in two dimensions.
Equilibrium and the Equilibrant
• Equilibrium: the net force on an object is
zero.
• When in equilibrium, the object is either
motionless or moves with constant
velocity.
Equilibrium and Equilibrant
• How do we add two vectors?
B
A
C
A
B
C
Because they form a closed triangle, the net force = 0.
Equilibrium and Equilibrant
• We can move vectors around as long as
we don’t change the direction (angle) or
magnitude.
• Suppose we only have two forces that do
not add up to zero.
• How do we find the third force that, when
added to the other two, would add up to
zero?
Equilibrium and Equilibrant
• The force that results in the net force of
zero is known as the equilibrant.
B
R
B
A
A
Equilibrant
B
A
R
Net Force = 0
Practice Problem
• Pg 151
• 2-4
Switching Gears
• Motion along an inclined plane.
FN
Θ
Θ
Fg
Practice Problems
• Pg 154
• 5-8