PROBLEM 8.60
The spring of the door latch has a constant of 1.8 lb/in. and in
the position shown exerts a 0.6-lb force on the bolt. The
coefficient of static friction between the bolt and the strike
plate is 0.40; all other surfaces are well lubricated and may be
assumed frictionless. Determine the magnitude of the force P
required to start closing the door.
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PROBLEM 8.61
In Problem 8.60, determine the angle that the face of the bolt
should form with the line BC if the force P required to close
the door is to be the same for both the position shown and the
position when B is almost at the strike plate.
PROBLEM 8.60 The spring of the door latch has a constant
of 1.8 lb/in. and in the position shown exerts a 0.6-lb force on
the bolt. The coefficient of static friction between the bolt and
the strike plate is 0.40; all other surfaces are well lubricated
and may be assumed frictionless. Determine the magnitude of
the force P required to start closing the door.
PROBLEM 8.62
A 5 wedge is to be forced under a 1400-lb machine base at A.
Knowing that the coefficient of static friction at all surfaces is 0.20,
(a) determine the force
P
required to move the wedge, (b) indicate
whether the machine base will move.
PROBLEM 8.63
Solve Problem 8.62 assuming that the wedge is to be forced under the
machine base at B instead of A.
PROBLEM 8.62 A 5 wedge is to be forced under a 1400-lb machine
base at A. Knowing that the coefficient of static friction at all surfaces
is 0.20, (a) determine the force P required to move the wedge,
(b) indicate whether the machine base will move.
PROBLEM 8.64
A 15 wedge is forced under a 50-kg pipe as shown. The coefficient of static
friction at all surfaces is 0.20. (a) Show that slipping will occur between the
pipe and the vertical wall. (b) Determine the force
P
required to move the
wedge.
PROBLEM 8.64 (Continued)
PROBLEM 8.65
A 15 wedge is forced under a 50-kg pipe as shown. Knowing that the
coefficient of static friction at both surfaces of the wedge is 0.20, determine
the largest coefficient of static friction between the pipe and the vertical wall
for which slipping will occur at A.
PROBLEM 8.66*
A 200-N block rests as shown on a wedge of negligible weight. The
coefficient of static friction
s is the same at both surfaces of the wedge, and
friction between the block and the vertical wall may be neglected. For
P 100 N, determine the value of
s for which motion is impending.
(Hint: Solve the equation obtained by trial and error.)
PROBLEM 8.67*
Solve Problem 8.66 assuming that the rollers are removed and that
s
is the
coefficient of friction at all surfaces of contact.
PROBLEM 8.66* A 200-N block rests as shown on a wedge of negligible
weight. The coefficient of static friction
s
is the same at both surfaces of
the wedge, and friction between the block and the vertical wall may be
neglected. For P 100 N, determine the value of
s
for which motion is
impending. (Hint: Solve the equation obtained by trial and error.)
PROBLEM 8.67* (Continued)