Civil Engineering - Applied Mechanics

31. 

Lami's theroem states that

A. three forces acting at a point are always in equilibrium
B. if three forces acting on a point can be represented in magnitude and direction by the sides of a triangle, the point will be in the state of equilibrium
C. three coplaner forces acting at a point will be in equilibrium, if each force is proportional to the sine of the angle between the other two
D. three coplaner forces acting at a point will be in equilibrium if each force is inversely proportional to the sine of the angle between the other two
E. none of these.

Answer: Option C

Explanation:

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32. 

Pick up the incorrect statement from the following. In case of suspension bridge due to rise in temperature,

A. dip of the cable increases
B. length of the cable increases
C. dip of the cable decreases
D. none of the these.

Answer: Option C

Explanation:

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33. 

If two forces acting at a point are in equilibrium, they must be equal in magnitude and their line of action must be along

A. the same line in the same sense
B. the same line in opposite sense
C. the perpendicular to both the lines
D. none of these.

Answer: Option B

Explanation:

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34. 

For lifting a load of 50 kg through a distance of 2.5 cm, an effort of 12.5 kg is moved through a distance of 40 cm. The efficiency of the lifting machine, is

A. 60%
B. 65%
C. 70%
D. 25%.

Answer: Option D

Explanation:

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35. 

Power can be expressed as

A. work/energy
B. work/time
C. work x time
D. work/distance.

Answer: Option B

Explanation:

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