Problem 3. The hook is acted on by three forces. Given that the
resultant is 90i kN, determine the magnitude of P and the angle,
.
y
P
R = F
Fx = 90 = P cos + 40 cos 60 - 30
30 kN
R=90i
x
60
90 + 30 40 cos 60 = P cos = Px
100 = P cos = Px = 100
(1)
Fy = 0
Problem 1 Given three forces in the x-y plane, A, B & C, where A
is 20# and acts at an unknown angle from the x-axis, B is 25#
and acts on a slope of 3H:4V and C is 26# and acts on a slope of
5H:12V. Given that the resultant R = A + B + C, find to
minimiz
Mech 234/5
Fall 03
EXAM 2
-Problem 1
Given points A(4, 3, 2), B(6, 1, -2) & C(8,
8, 4), find the angle between the lines AB & AC.
AB = 2i - 2j - 4k
AC = 4i + 5j + 2k
AB AC = AB AC cos = 8 10 8
= -10
AB = (4 + 4 + 16)1/2 = 4.90
AC = (16 + 25 + 4)1/2 = 6.71
#1. A 6-ft long fishing rod AB is anchored in the sand. The force in the
fishing line, BC, from the fish pulling is 10 lb. Determine the moment
due to this force about A where the fishing rod is anchored in the sand.
y
B
F=10#
C
12
30
45
z
A
sandy beach
x
#1. A force, F = 12i + 3j +4k (lbs), passes through the point
A( -3, 4, + 12). A couple, C = 10k, is applied to the same point.
Find an equivalent force system at the origin.
Draw what you have and see what you need.
Equivalent system means:
R = F = F = 1
Problem 1. A 200-kg load is supported by the rope-and-pulley arrangement.
Determine the magnitude and direction of the force P required at the free end
of the rope to maintain equilibrium.
The cable tension is the same
throughout the length of the cable.
3. Use the method of trigonometry to determine the resultant
of the two forces acting on the eye-hook as shown. Give your
answer in polar coordinate and rectangular coordinate form.
25
25
5N
8N
Definition:
R = F = A + B,
Add the 8 N and 5 N forces head to