**621. Which of the following is not the unit of work, energy and heat ?**

A.Kcal

B.Kg m

C.KWhr

**D.Hp**

**622. The weight of a body is due to**

A.Centripetal force of earth

**B.Gravitational force of attraction towards the centre of the earth**

C.Forces experienced by body in atmosphere

D.Force of attraction experienced by particles

**623. The forces, which meet at one point, but their lines of action do not lie in a plane, are called**

A.Coplanar non-concurrent forces

**B.Non-coplanar concurrent forces**

C.Non-coplanar non-concurrent forces

D.Intersecting forces

**624. When trying to turn a key into a lock, following is applied**

A.Coplanar force

**B.Couple**

C.Lever

D.Moment

**625. According to principle of transmissibility of forces, the effect of a force upon a body is**

A.Maximum when it acts at the centre of gravity of a body

B.Different at different points in its line of action

**C.The same at every point in its line of action**

D.Minimum when it acts at the C.G. of the body

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

A.Energy

B.Mass

**C.Momentum**

D.Angle

**627. The magnitude of two forces, which when acting at right angle produce resultant force of ?10kg and when acting at 60° produce resultant of ?13kg These forces are**

A.2 and ?6

**B.3 and 1 kg**

C.?5 and ?5

D.2 and 5

**628. A number of forces acting at a point will be in equilibrium if**

A.Their total sum is zero

B.Two resolved parts in two directions at right angles are equal

**C.Sum of resolved parts in any two perpendicular directions are both zero**

D.All of them are inclined equally

**629. Two non-collinear parallel equal forces acting in opposite direction**

A.Balance each other

B.Constitute a moment

**C.Constitute a couple**

D.Constitute a moment of couple

**630. According to principle of moments**

A.If a system of coplanar forces is in equilibrium, then their algebraic sum is zero

**B.If a system of coplanar forces is in equilibrium, then the algebraic sum of their moments about any point in their plane is zero**

C.The algebraic sum of the moments of any two forces about any point is equal to moment of their-resultant about the same point

D.Positive and negative couples can be balanced

**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**