Support Reactions of a Trapezoidal Slab with Three Points of Support

Situation
A reinforced concrete slab in the shape of an isosceles trapezoid weighs 3600 N/m2. It is supported on the three points as shown in the figure.
 

eq-parallel-forces-trapezoid-slab.gif
  1. Find the reaction at A.
    A.   16,848 N
    B.   6,716 N
    C.   13,372 N
    D.   2,010 N
  2. Find the reaction at B.
    A.   16,848 N
    B.   6,716 N
    C.   13,372 N
    D.   2,010 N
  3. Find the reaction at C.
    A.   16,848 N
    B.   6,716 N
    C.   13,372 N
    D.   2,010 N

 

Equation of the Locus of a Moving Point

Definition of a Locus
Locus is a Latin word which means "place". In mathematics, locus is the set of points that satisfies the same geometrical properties. In most cases, the relationship of these points is defined according to their position in rectangular coordinates.
 

Example 1
Determine the equation of the curve such that the sum of the distances of any point of the curve from two points whose coordinates are (-3, 0) and (3, 0) is always equal to 8.
    A.   4x2 + 49y2 - 343 = 0
    B.   7x2 + 16y2 - 112 = 0
    C.   7x2 - 16y2 + 112 = 0
    D.   4x2 - 49y2 + 343 = 0
 

01 - Example of Mixture Related Problem

Problem
In a class experiment, a student needs 5 liters of 6% solution. He found a 4% and a 10% solution in the laboratory. How many liters of each solution should he mix in order to obtain 5 liters of 6% solution?
A. 3.33 liters of 4% and 1.67 liters of 10% solution
B. 1.67 liters of 4% and 3.33 liters of 10% solution
C. 3.67 liters of 4% and 1.33 liters of 10% solution
D. 1.33 liters of 4% and 3.67 liters of 10% solution
 

Length of Belt Connecting Two Pulleys

Problem
Two flat belt pulleys have a center to center distance of 137 cm, and diameters of 72 cm and 36 cm, respectively. Neglecting the sagging of belt...

  1. compute the length of belt if both pulleys will rotate in the same direction.
    A.   464.5 cm C.   446.0 cm
    B.   553.1 cm D.   535.4 cm
  2. compute the length of belt if the belt will be cross-connected to make the pulleys rotate in opposite directions.
    A.   654.1 cm C.   564.2 cm
    B.   465.2 cm D.   645.1 cm
  3. determine the distance of the point from the center of the bigger pulley where the belt will cross when cross-connected.
    A.   91.3 cm C.   89.4 cm
    B.   100.4 cm D.   98.7cm