1. If F1=50lb upward and F2=60lb upward ,the resultant and the direction of the resultant along the common line of action would be

(A)10lb down

(B)90lb up

(C)110lb up

(D)210lb up

2. A body that weighs 50lb is placed in contact with an inclined plane surface. The coefficient of friction between the surfaces is 0.25 and the angle between the inclined surface and the horizontal reference plane in 28 degrees. In order to keep the body from sliding, by using an applied force whose line of action is parallel to the inclined supporting surface, what is the last permissible magnitude of force?

(A)6.3lb

(B)12.5

(C)14

(D)50

3. The condition that must exist when a body is at rest is that the magnitude of the resultant of forces acting on the body must be

(A)0.

(B)20 percent

(C)dependent upon the incline

(D)external

4. When solving a practical problem where the magnitudes of two forces are unknown, your calculations can be simplified if one of the reference axes coincides with the line of action of one the unknown forces and the other reference axis is

(a)equal zero

(B)horizontal to that line of action

(C)perpendicular to that line of action

(D)vertical to that line of action

5. What will be the result when the applied horizontal force and the friction force form a couple, the lines of action are parallel, and the magnitude are equal? They will

(A)act in the same direction

(B)cause the body to rotate

(C)create a mutual force

(D)create friction