Engineering Mechanics

41. If n = number of members andy = number of joints, then for a perfect frame, n =

1. j-2
2. 2j-l
3. 2/-3
4. 3/-2
5. 2/ -4.

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42. If rain is falling in the opposite direction of the movement of a pedestrain, he has to hold his umbrella

1. more inclined when moving
2. less inclined when moving
3. more inclined when standing
4. less inclined when standing
5. none of the above.

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43. If three forces acting in different planes can be represented by a triangle, these will be in

1. non-equilibrium
2. partial equilibrium
3. full equilibrium
4. unpredictable
5. none of the above.

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44. If two equal forces of magnitude P act at an angle 9°, their resultant will be

1. P/2 cos 9/2
2. IP sin 9/2
3. 2P tan 9/2
4. IP cos 9/2
5. Psin 9/2.

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45. In actual machines

1. mechanical advantage is greater than velocity ratio
2. mechanical advantage is equal to velocity ratio
3. mechanical advantage is less than velocity ratio
4. mechanical advantage is unity
5. none of the above.

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46. In detennining 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

1. two members with unknown forces of the frame
2. three members with unknown forces of the frame
3. four members with unknown forces of the frame
4. three members with known forces of the frame
5. four members with two known forces.

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47. In ideal machines

1. mechanical advantage is greater than velocity ratio
2. mechanical advantage is equal to velocity ratio
3. mechanical advantage is less than velocity ratio
4. mechanical advantage is unity
5. none of the above.

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48. In the equation of virtual work, following force is neglected

1. reaction of any smooth surface with which the body is in contact
2. reaction of a rough surface of a body which rolls on it without slipping
3. reaction at a point or an axis, fixed in space, around which a body is con-strained to turn
4. all of the above
5. none of the above.

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49. In the lever of third order, load W, effort P and fulcrum F are oriented as follows

1. W between P and F
2. F between W and P
3. P between W and F
4. W, P and F all on one side
5. none of the above.

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50. Kinetic friction is the

1. tangent of angle between normal reaction and the resultant of normal reaction and the limiting friction
2. ratio of limiting friction and normal reaction
3. the friction force acting when the body is just about to move
4. the friction force acting when the body is in motion
5. dynamic friction.

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