10/29/07
1:38 PM
Page 22
Dynamic Graphics/Media Bakery
c02.qxd
The properties of force systems must be thoroughly understood by the engineers who design devices such as this
crane and its lifting harness. Try to visualize the forces present in the variou

The force F acting on a body has two effects:
the first one is the tendency to push or pull the body in the direction
of the force, and the second one is to rotate the body about any fixed
axis which does not intersect nor is parallel to the line of the

1. As a trailer is towed in the forward direction, the
force F = 500 N is applied as shown to the ball of the
trailer hitch. Determine the moment of this about
point O.
(2/43)
MO ?
dx
Fy
Fx
Fx 500sin 30
Fx 250 N
Fy 500cos30
Fy 433 N
M
+
O
Fx d y Fy d x 2

Moment
r
F
r
F
Translation
d
Translation + Rotation
r
This rotation tendency is known as moment M of force (torque)
Axis of rotation may be any line which neither intersects nor
parallel to the line of action of force
r
Magnitude of moment depends on m

Seminar Problems
September 28, 2016
1. Problem
(e) n=3i - j + 2k, P(0,2,-3)
(f) n=i + 4j, P(1,0,-9)
Find parametric equation for the line
passes through the point P and is parallel to the vector v.
4. Problem
Find an equation of the plane that
passes thro