1. For triangle ABC the side AB represents magnitude of force and altitude of triangle represents moment arm from moment centre C then moment about C is ____.
For triangle ABC the side AB represents magnitude of force and altitude of triangle represents moment arm from moment centre C then moment about C is

(a) Area of triangle ABC (b) ½ area of triangle (c) 2 area of triangle ABC (d) 3 area of triangle ABC

Ans.: (c) Explanation : Moment about R = F ´ h Area of DABC = 1 2 ´ F ´ h

2. A vertical force of F acting in second quadrant in –xy plane at (–2, 3) m. If F = 98 N, the magnitude of moment about origin is

A vertical force of F acting in second quadrant in –xy plane at (–2, 3) m. If F = 98 N, the magnitude of moment about origin is

(a) 196 Nm (b) 98 Nm (c) 294 Nm (d) 0 Nm

Ans.: (a) Explanation : Moment = F× d F = 38, d = – 2 me origin = 98 ´ (– 2) = – 196 N.m

3. A force of 20 N acting through points P (2,1) and Q (1,2), its moment @ 0 (0,0) will be ______.

A force of 20 N acting through points P (2,1) and Q (1,2), its moment @ 0 (0,0) will be

(a) 28.28N.m (b) 28N.m (c) 14.14N.m (d) -14.14N.m

Ans.: (a) Explanation : Moment @ (0,0) = 20 cos 45 ´ 1 + 20 sin 45 ´ 2 = 14.14 + 14.14 = 28.28 N.m

4. A force of 200 N acting at A (4, 5) makes an angle 35° with the vertical, its moment about the origin is ______.

A force of 200 N acting at A (4, 5) makes an angle 35° with the vertical, its moment about the origin is

(a) -32.64N.m (b) 950.4N.m (c) 458.88N.m (d) 491.52N.m

Ans.: (a) Explanation : Moment of origin = + 114.72 ´ 4 – 163.84 ´ 3 = (114.72 ´ 4) – (163.84 ´ 3) = – 32.64 N.m

5. A force of 50 N acting tangentially to a circle of radius 6 m. Its moment about diametrically opposite point will be ____.

A force of 50 N acting tangentially to a circle of radius 6 m. Its moment about diametrically opposite point will be

(a) 150 Nm (b) 600 Nm (c) 60 Nm (d) 300 Nm

Ans.: (b) Explanation : Moment about B = F ´ d = 50 ´ 12 = 600 Nm

6. A forces of 10 N each acting along sides of equilateral triangle of side 3 m. The moment of force system about apex of triangle is ______.

A forces of 10 N each acting along sides of equilateral triangle of side 3 m. The moment of force system about apex of triangle is

(a) 25.90 Nm (b) 60 Nm (c) 30 Nm (d) 12.95 Nm

Ans.: (a) Explanation : tan 60° = h 1.5 \ h = 2.59 m Moment at C = F×d = 10 ´ 2.59 = 25.90 N×m

7. A door of width 1.8 m can rotate if a moment of 20 Nm is applied. The minimum force that can be applied to open it is ____.

A door of width 1.8 m can rotate if a moment of 20 Nm is applied. The minimum force that can be applied to open it is

(a) 20 N (b) 1.8 N (c) 11.11 N (d) None of these

Ans.: (c) Explanation : M = F×d 20 = F ´ 1.8 F = 11.11 N

8. A force of 200 N is acting through points A (2, 3) and B (2, 1). The moment of force about point O (0, 0) is

A force of 200 N is acting through points A (2, 3) and B (2, 1). The moment of force about point O (0, 0) is

(a) 400 Nm (b) 200 Nm (c) 600 Nm (d) 100 Nm

Ans.: (a) Explanation : MO = (200 ´ 2) R = 400 Nm

9. Moment of a couple is

(a) Depends upon axis (b) Independent of a point (c) Depends upon point (d) None of the above.

Ans.: (b) Explanation : Moment of couple : The moment of a couple is the product of the force and the arm of couple. M = F ´ d

10. A lever AB = 2 m long is inclined at 35° with horizontal A forces of 180 N is acting at B vertically downwards. The moment about ‘A’ is

A lever AB = 2 m long is inclined at 35° with horizontal A forces of 180 N is acting at B vertically downwards. The moment about ‘A’ is

(a) 29.5 Nm (b) 295 Nm (c) 2950 Nm (d) 2.950 Nm

Ans.: (b) Explanation : Moment about A = F× d = 180 ´ 2 cos 35° = 295 Nm

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