29. 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

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30. 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

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31. 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

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32. 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

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33. 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

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34. 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

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35. 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

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