### Engineering Mechanics

11. A heavy string attached at two ends at same horizontal level and when central dip is very small approaches the following curve

1. catenary
2. parabola
3. hyperbola
4. elliptical
5. circular arc.

parabola

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

1. their total sum is zero
2. two resolved parts in two directions at right angles are equal
3. sum of resolved parts in any two per-pendicular directions are both zero
4. all of them are inclined equally
5. none of the above.

sum of resolved parts in any two per-pendicular directions are both zero

13. A pair of smith's tongs is an example of the lever of

1. zeioth order
2. first order
3. second order
4. third order
5. fourth order.

second order

14. A particle inside a hollow sphere of radius r, having coefficient of friction -rr can rest upto height of

1. r/2
2. r/A
3. r/%
4. 0.134 r
5. 3r/8.

0.134 r

15. A particle moves along a straight line such that distance (x) traversed in t seconds is given by x = t2 (t - 4), the acceleration of the particle will be given by the equation

1. 3t2-lt
2. 3t2+2t
3. 6f-8
4. 6f-4
5. 6t2-8t.

6f-8

16. A projectile is fired at an angle 9 to the vertical. Its horizontal range will be maximum when 9 is

1. 30°
2. 45°
3. 60°
4. 90°.

45°

17. A sample of metal weighs 219 gms in air, 180 gms in water, 120 gms in an unknown fluid. Then which is correct statement about density of metal

1. density of metal can't be determined
2. metal is twice as dense as water
3. metal will float in water
4. metal is twice as dense as unknown fluid
5. none of the above.

density of metal can't be determined

18. A semi-circular disc rests on a horizontal surface with its top flat surface horizontal and circularportion touching down. The coefficient of friction between semi-cricular disc and horizontal surface is \i.This disc is to be pulled by a horizontal force applied at one edge and it always remains horizontal. When the disc is about to start moving, its top horizontal force will

1. remain horizontal
2. slant up towards direction of pull
3. slant down towards direction of pull
4. unpredictable
5. none of the above.

slant down towards direction of pull

19. A single force and a couple acting in the same plane upon a rigid body

1. balance each other
2. cannot balance each other
3. produce moment of a couple
4. are equivalent
5. none of the above.

cannot balance each other

20. A trolley wire weighs 1.2 kg per meter length. The ends of the wire are attached to two poles 20 meters apart. If the horizontal tension is 1500 kg find the dip in the middle of the span

1. 2.5 cm
2. 3.0 cm
3. 4.0 cm
4. 5.0 cm
5. 2.0 cm.