Name
Period
Date
Rotation: Worksheet 4 Static Equilibrium
For each problem:
 Draw an extended force diagram of the object.
 Write the static equilibrium equation for the torques acting on the object.
 Use the equation to calculate the requested quantity.
1. A 0.50 kg box is placed ¾ of the way
along a meter stick of length L and
mass 0.100 kg. How much mass must
be hung from the string in order to hold
the meter stick at rest?
2. A uniform meter stick, supported at the 35.0 cm
mark, is balanced when a 0.70 N weight is hung
at the 0.0 cm mark. What is the mass of the
meter stick?
0.70 N
Rotation: Worksheet 4 Static Equilibrium
3. A steel beam of mass m and length L is
lifted so that it tilts at 15°. What is the
minimum force required to hold the beam
at 15°?
page 2
Lifting Force
4. A 3.0 m long uniform plank of mass 60. kg is
placed on top of two sawhorses one at each
end. A 75 kg painter stands 1.0 m from the left
end. What upward force does each sawhorse
exert on the plank to keep this system in static
equilibrium? Begin by drawing an extended
force diagram of the plank. (Remember, you can choose any axis around which to
sum the torques since it is in static equilibrium.
5. A banner is suspended from a horizontal pivoted pole, as
shown below. The pole is 2.10 m long and weighs 175 N. The
105 N banner is suspended 1.80 m from the pivot point or axis of
rotation.
a. On the diagram below, draw and label vectors to represent
all the forces acting on the pole. Show each force vector
(not components) originating at its point of application.
Rotation: Worksheet 4 Static Equilibrium
page 3
b. What is the tension in the cable supporting the pole? If you need to draw
anything besides what you have shown in part (a) to assist in your solution, use
the space below. Do NOT add anything to the figure in part (a).
6. A uniform ladder 10. m long and weighing 50. N rests against a
“smooth” vertical wall as shown. The ladder is just on the verge of
slipping when it makes a 50.° angle with the ground.
a. On the diagram below, draw and label vectors to represent all the
forces acting on the ladder. Show each force vector (not
components) originating at its point of application.
b. Find the coefficient of static friction between the ladder and the ground. If you
need to draw anything besides what you have shown in part (a) to assist in your
solution, use the space below. Do NOT add anything to the figure in part (a).
Rotation: Worksheet 4 Static Equilibrium
page 4
7. A uniform beam 5.0 m long is attached to a wall by a hinge that
allows the beam to rotate at the left end. Its right end is
supported by a cable that makes an angle of 53° with the
horizontal and which exerts a 390 N force of tension. A person
weighing 600. N stands 2.0 m from the wall on the left side.
a. On the diagram below, draw and label vectors to represent
all the forces acting on the beam. Show each force vector
(not components) originating at its point of application.
b. Find the mass of the beam. If you need to draw anything besides what you have
shown in part (a) to assist in your solution, use the space below. Do NOT add
anything to the figure in part (a).
c. Find the horizontal and vertical components of the force exerted by the hinge on
the beam.
Rotation: Worksheet 4 Static Equilibrium
page 5
8. A man with mass 55 kg stands 2.0 m away from
the wall on a uniform 6.0 m beam, as shown
below. The mass of the beam is 40. kg. The angle
the cable makes with the horizontal is 30.°. Find
the force the wall exerts on the hinge and the
tension in the cable.
a. On the diagram below, draw and label vectors
to represent all the forces acting on the pole.
Show each force vector (not components)
originating at its point of application.
b. Find the tension in the cable. If you need to draw anything besides what you have
shown in part (a) to assist in your solution, use the space below. Do NOT add
anything to the figure in part (a).