**21. Which of the following is not a scalar quantity**

- Time
- mass
- volume
- density
- acceleration

Ans. e) Acceleration

**22. According to principle of transmissibility of forces, the effect of a force upon a body is the same at every point in its line of action. (True/False)**

Ans. True

**23. Which of the following is a vector quantity**

- energy
- mass
- momentum
- angle
- speed

Ans. Momentum

**24. A number of forces acting at a point will be in equilibrium if sum of resolved parts in any two perpendicular direction are both zero (yes/no)**

Ans. Yes

**25. Two non-co linear parallel equal forces acting in opposite direction constitute a couple (yes/no)**

Yes.

**26. According to principle of moment, if a system of coplanar forces is in equilibrium, then the algebraic sum of their moments about any point in their plane is zero.Â **

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

- weight
- velocity
- acceleration
- force
- moment

Ans. a) weight

**28. if a rigid body is in equilibrium under the action of three forces then,â€™**

- these forces are equal
- the lines of action of these forces meet in a point
- the line of action of these forces are parallel
- (b) and (c) above
- none of above

Ans. d)

**29. Dâ€™Alembertâ€™s principle is used for**

- reducing the problem of kinetics to equivalent statics problem
- determining stresses in the truss
- stability of floating bodies
- designing safe structures
- solving kinematic problem

Ans. a) reducing the problem of kinetics to equivalent statics problem.

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

- the floor is smooth, the wall is rough
- the floor is rough, the wall is smooth
- the floor and wall both are smooth surfaces
- the floor and wall both are rough surfaces
- will be in equilibrium under all conditions

Ans. c) the floor and wall both are smooth surfaces