311. If the value of P in Fig.
P-310 is
180 lb, determine the angle θ at which it
323. The truss shown in Fig. P-323 is
must be inclined with the smooth lane to
supported by a hinge at A and a roller at
hold the 300-lb box in equilibrium.
B. A load of 20 kN is applied at C.
Determine the reactions at A and B.
312. Determine the magnitudes of P and
F necessary to keep the concurrent
324. A wheel of 10-in radius carries a
force system shown in Fig. P-312 in
load of 1000 lb, as shown in Fig. P-324.
equilibrium.
(a) Determine the horizontal force P
applied at the center which is necessary
313. Fig. P-313 represents the to start the wheel over a 5-in. block.
concurrent force system acting at a joint Also find the reaction at the block.
of a bridge truss. Determine the values
of P and F to maintain equilibrium of the
forces. (b) If the force P may be inclined at any
angle with the horizontal, determine the
minimum value of P to start the wheel
314. The five forces shown in Fig. P-314 over the block; the angle P makes with
are in equilibrium. Compute the values the horizontal; and the reaction at the
of P and F. block.
315. The 300-lb force and the 400-lb 325. Determine the amount and
force shown in Fig. P-315 are to be held direction of the smallest force P required
in equilibrium by a third force F acting at to start the wheel in Fig. P-325 over the
an unknown angle θ with the horizontal. block. What is the reaction at the block?
Determine the values of F and θ.
327. Forces P and F acting along the
316. Determine the values of the angles bars shown in Fig. P-327 maintain
α and θ so that the forces shown in Fig. equilibrium of pin A. Determine the
P-316 will be in equilibrium. values of P and F.
317. The system of knotted cords shown 328. Two weightless bars pinned
in Fig. P-317 support the indicated together as shown in Fig. P-328 support
weights. Compute the tensile force in a load of 35 kN. Determine the forces P
each cord. and F acting respectively along bars AB
and AC that maintain equilibrium of pin endless chain looped over them in two
A. loops. In one loop is mounted a movable
pulley supporting a load W. Neglecting
friction, determine the maximum load W
334. Determine the reactions for the that can just be raised by a pull P
beam loaded as shown in Fig. P-334. supplied as shown.
335. The roof truss in Fig. P-335 is 340. For the system of pulleys shown in
supported by a roller at A and a hinge at Fig. P-340, determine the ratio of W to P
B. Find the values of the reactions. to maintain equilibrium. Neglect axle
friction and the weights of the pulleys.
336. The cantilever beam shown in Fig.
P-336 is built into a wall 2 ft thick so that 341. If each pulley shown in Fig. P-340
it rests against points A and B. The weighs 36 kg and W = 720 kg, find P to
beam is 12 ft long and weighs 100 lb per maintain equilibrium.
ft.
342. The wheel loads on a jeep are
337. The upper beam in Fig. P-337 is given in Fig. P-342. Determine the
supported at D and a roller at C which distance x s o that the reaction of the
separates the upper and lower beams. beam at A is twice as great as the
Determine the values of the reactions at reaction at B.
A, B, C, and D. Neglect the weight of the
beams.
343. The weight W of a traveling crane
is 20 tons acting as shown in Fig. P-343.
338. The two 12-ft beams shown in Fig. To prevent the crane from tipping to the
3-16 are to be moved horizontally with right when carrying a load P of 20 tons,
respect to each other and load P shifted a counterweight Q is used. Determine
to a new position on CD so that all three the value and position of Q so that the
reactions are equal. How far apart will crane will remain in equilibrium both
R2 and R3 then be? How far will P be when the maximum load P is applied
from D? and when the load P is removed.
339. The differential chain hoist shown
in Fig. P-339 consists of two concentric
pulleys rigidly fastened together. The
pulleys form two sprockets for an
