Applied Mechanics and Graphic Statics

231. The displacement of a particle which moves along a straight line is given by S = 4t³ + 3t²- 10 where 'S' is in meters and t is in seconds. The time taken by the particle to acquire a velocity of 18 m/sec from rest, is

1. ½ sec
2. 1 sec
3. 1.2 sec
4. 1.5 sec

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232. The ends of a string weighing w/metre are attached to two points at the same horizontal level. If the central dip is very small, the horizontal tension of the string throughout is

1. wl/4d
2. wl²/4d
3. wl²/8d
4. wl²/16d

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233. The equation of motion of a particle starting from rest along a straight line is x = t³ - 3l³ + 5. The ratio of the velocities after 5 sec and 3 sec will be

1. 2
2. 3
3. 4
4. 5

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234. Which one of the following statements is true?

1. The tangent of the angle of friction is equal to coefficient of friction
2. The angle of repose is equal to angle of friction
3. The tangent of the angle of repose is equal to coefficient of friction
4. All the above

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235. The following factor affects the orbit of a satellite up to an altitude of 720 km from the earth's surface

1. Uneven distribution of the gravitational field
2. Gravity of the sun and the moon
3. Aerodynamic forces
4. None of these

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236. The following is in unstable equilibrium

1. A uniform solid cone resting on a generator on a smooth horizontal plane
2. A uniform solid cone resting on its base on a horizontal plane
3. A solid cube resting on one edge
4. A satellite encircling the earth

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237. The following is not a law of static friction:

1. The force of friction always acts in a direction opposite to that in which the body tends to move
2. The force of friction is dependent upon the area of contact
3. The force of friction depends upon the roughness of the surface
4. The magnitude of the limiting friction bears a constant ratio to the normal reaction between two surfaces

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238. The following statement is one of the laws of Dynamic friction

1. The force of friction always acts in a direction opposite to that in which a body is moving
2. The magnitude of the kinetic friction bears a constant ratio to the normal reaction between two surfaces. The ratio being slightly less than that in the case of limiting friction
3. For moderate speeds the force of friction remains constant but decreases slightly with the increase of speed
4. All the above

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239. The force acting on a point on the surface of a rigid body may be considered to act

1. At the centre of gravity of the body
2. On the periphery of the body
3. On any point on the line of action of the force
4. At any point on the surface normal to the line of action of the force

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240. The force polygon representing a set of forces in equilibrium is a

1. Triangle
2. Open polygon
3. Closed polygon
4. Parallelogram

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