PROBLEM 4.1
The boom on a 4300-kg truck is used to unload a pallet of shingles of mass 1600 kg. Determine the reaction at each of the two (a) rear wheels B, (b) front wheels C.
SOLUTION
WA = mA g = (1600 kg ) 9.81 m/s 2
= 15696 N
(
)
or
WA = 15
PROBLEM 3.1
A 13.2-N force P is applied to the lever which controls the auger of a snowblower. Determine the moment of P about A when is equal to 30.
SOLUTION
First note Px = P sin = (13.2 N ) sin 30 = 6.60 N
Py = P cos = (13.2 N ) cos 30 = 11.4
PROBLEM 5.1
Locate the centroid of the plane area shown.
SOLUTION
A, in 2
x , in.
y , in.
xA, in 3
yA, in 3
1 2
8 6 = 48
16 12 = 192
-4
9 6
-192
432 1152 1584
8
1536 1344
240
xA 1344 in 3 = A 240 in 2 yA 1584 in 3 = A 240 in 2
Th
PROBLEM 6.1
Using the method of joints, determine the force in each member of the truss shown. State whether each member is in tension or compression.
SOLUTION
FBD Truss:
M B = 0: ( 6.25 m ) C y - ( 4 m )( 315 N ) = 0
Fy = 0: By - 315 N + C y = 0
PROBLEM 7.1
Determine the internal forces (axial force, shearing force, and bending moment) at point J of the structure indicated: Frame and loading of Prob. 6.77.
SOLUTION
Fx = 0: - F = 0
FBD JD:
Fy = 0: V - 20 lb - 20 lb = 0
F=0
V = 40.0 lb
M J
PROBLEM 8.1
Determine whether the block shown is in equilibrium, and find the magnitude and direction of the friction force when = 30o and P = 200 N.
SOLUTION
FBD block:
Fn = 0: N - (1000 N ) cos 30 - ( 200 N ) sin 30 = 0 N = 966.03 N
Assume equi