**631. Which of the following is not a vector quantity**

**A.Weight**

B.Velocity

C.Acceleration

D.Force

**632. According to law of triangle of forces**

A.Three forces acting at a point will be in equilibrium

B.Three forces acting at a point can be represented by a triangle, each side being proportional to force

**C.If three forces acting upon a particle are represented in magnitude and direction by the sides of a triangle, taken in order, they will be in equilibrium**

D.If three forces acting at a point are in equilibrium, each force is proportional to the sine of the angle between the other two

**633. If a rigid body is in equilibrium under the action of three forces, then**

A.These forces are equal

B.The lines of action of these forces meet in a point

C.The lines of action of these forces are parallel

**D.(B) and (C) above**

**634. If two forces each equal to P in magnitude act at right angles, their effect may be neutralised by a third force acting along their bisector in opposite direction whose magnitude is equal to**

A.2P

B.P/2

**C.?2P**

D.P/?2

**635. D’ Alembert’s principle is used for**

**A.Reducing the problem of kinetics to equivalent statics problem**

B.Determining stresses in the truss

C.Stability of floating bodies

D.Designing safe structures

**636. A heavy ladder resting on floor and against a vertical wall may not be in equilibrium, if**

A.The floor is smooth, the wall is rough

B.The floor is rough, the wall is smooth

**C.The floor and wall both are smooth surfaces**

D.The floor and wall both are rough surfaces

**637. According to Lami’s theorem**

A.Three forces acting at a point will be in equilibrium

B.Three forces acting at a point can be represented by a triangle, each side being proportional to force

C.If three forces acting upon a particle are represented in magnitude and direction by the side of a triangle, taken in order, they will be in equilibrium

**D.If three forces acting at a point are in equilibrium, each force is proportional to the sine of the angle between the other two**

**638. The product of either force of couple with the arm of the couple is called**

A.Resultant couple

B.Moment of the forces

C.Resulting couple

**D.Moment of the couple**

**639. In determining stresses in frames by methods of sections, the frame is divided into two parts by an imaginary section drawn in such a way as not to cut more than**

A.Two members with unknown forces of the frame

**B.Three members with unknown forces of the frame**

C.Four members with unknown forces of the frame

D.Three members with known forces of the frame

**640. Two coplaner couples having equal and opposite moments**

A.Balance each other

**B.Can not balance each other**

C.Are equivalent

D.Produce a moment of couple

**NOTE IF YOU THINK ANY OF THE MCQ ABOVE IS WRONG. PLEASE COMMENT WITH CORRECT ANSWER AND ITS DETAIL EXPLANATION IN COMMENT BOX. THANK YOU**