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CHAPTER 3
PROBLEM 3.1
A crate of mass 80 kg is held in the position shown. Determine
(a) the moment produced by the weight W of the crate about E,
(b) the smallest force applied at B that creates a moment of equal
magnitude and opposite sense about E.
PROBLEM 3.2
A crate of mass 80 kg is held in the position shown. Determine
(a) the moment produced by the weight W of the crate about E,
(b) the smallest force applied at A that creates a moment of equal
magnitude and opposite sense about E, (c) the magnitude, sense,
and point of application on the bottom of the crate of the smallest
vertical force that creates a moment of equal magnitude and
opposite sense about E.
PROBLEM 3.3
It is known that a vertical force of 200 lb is required to remove the
nail at C from the board. As the nail first starts moving, determine
(a) the moment about B of the force exerted on the nail, (b) the
magnitude of the force P that creates the same moment about B if
α = 10°, (c) the smallest force P that creates the same moment
about B.
PROBLEM 3.4
A 300-N force is applied at A as shown. Determine
(a) the moment of the 300-N force about D, (b) the
smallest force applied at B that creates the same moment
about D.
PROBLEM 3.5
A 300-N force is applied at A as shown. Determine
(a) the moment of the 300-N force about D, (b) the
magnitude and sense of the horizontal force applied at C
that creates the same moment about D, (c) the smallest
force applied at C that creates the same moment about D.
PROBLEM 3.6
A 20-lb force is applied to the control rod AB as shown. Knowing that the length of
the rod is 9 in. and that α = 25°, determine the moment of the force about Point B by
resolving the force into horizontal and vertical components.
PROBLEM 3.7
A 20-lb force is applied to the control rod AB as shown. Knowing that the length of
the rod is 9 in. and that α = 25°, determine the moment of the force about Point B
by resolving the force into components along AB and in a direction perpendicular
to AB.
PROBLEM 3.8
A 20-lb force is applied to the control rod AB as shown. Knowing that the length
of the rod is 9 in. and that the moment of the force about B is 120 lb ∙ in. clockwise,
determine the value of α.
