# Mechanics & Strength of Materials 8

Objective Questions and Answer: Mechanics & Strength of Materials 8

Subject:  Mechanics & Strength of Materials 8

Part 8: Objective questions and answers of Mechanics & Strength of Materials

Q1. Limiting force of friction is the

a) Tangent of angle between normal-reaction and the resultant of normal reaction and limiting friction

b) Ratio of limiting friction and normal reaction

c) The friction force acting when the body is just about to move

d) The friction force acting when the body is in motion

Q2. Coulomb friction is the friction between

a) Bodies having relative motion

b) Two dry surfaces

c) Two lubricated surfaces

d) Solids and liquids

Q3. Dynamic friction as compared to static friction is

a) Same

b) More

c) Less

d) May be less of more depending on nature of surfaces and velocity

Q4. Tangent of angle of friction is equal to

a) Kinetic friction

b) Limiting friction

c) Angle of repose

d) Coefficient of friction

Q5. Kinetic friction is the

a) Tangent of angle between normal reaction and the resultant of normal reaction and the limiting friction

b) Ratio of limiting friction and normal reaction

c) The friction force acting when the body is just about to move

d) The friction force acting when the body is in motion

Q6. A semi-circular disc rests on a horizontal surface with its top flat surface horizontal and circular portion touching down. The coefficient of friction between semi-circular 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

a) Remain horizontal

b) Slant up towards direction of pull

c) Slant down towards direction of pull

d) Unpredictable

Q7. A particle inside a hollow sphere of radius r, having coefficient of friction -rr can rest upto height of

a) R/2

b) R/A

c) R/%

d) 0.134 r

Q8. The algebraic sum of moments of the forces forming couple about any point in their plane is

a) Equal to the moment of the couple

b) Constant

c) Both of above are correct

d) Both of above are wrong

Q9. A single force and a couple acting in the same plane upon a rigid body

a) Balance each other

b) Cannot balance each other

c) Produce moment of a couple

d) Are equivalent

Q10. If three forces acting in one plane upon a rigid body, keep it in equilibrium, then they must either

a) Meet in a point

b) Be all parallel

c) At least two of them must meet

d) All the above are correct

Q11. The maximum frictional force which comes into play when a body just begins to slide over another surface is called

a) Limiting friction

b) Sliding friction

c) Rolling friction

d) Kinematic friction

Q12. The co-efficient of friction depends upon

a) Nature of surfaces

b) Area of contact

c) Shape of the surfaces

d) Ail of the above.

Q13. The necessary condition for forces to be in equilibrium is that these should be

a) Coplanar

b) Meet at one point ;

c) Both (a) and (b) above

d) All be equal

Q14. If three forces acting in different planes can be represented by a triangle, these will be in

a) Non-equilibrium

b) Partial equilibrium

c) Full equilibrium

d) Unpredictable

Q15. If n = number of members and j = number of joints, then for a perfect frame, n =

a) J-2

b) 2j-l

c) 2j-3

d) 3j-2

Q16. A body moves, from rest with a constant acceleration of 5 m per sec. The distance covered in 5 sec is most nearly

a) 38 m

b) 62.5 m

c) 96 m

d) 124 m

Q17. A flywheel on a motor goes from rest to 1000 rpm in 6 sec. The number of revolutions made is nearly equal to

a) 25

b) 50

c) 100

d) 250

Q18. Which of the following is the locus of a point that moves in such a manner that its distance from a fixed point is equal to its distance from a fixed line multiplied by a constant greater than one

a) Ellipse

b) Hyperbola

c) Parabola

d) Circle

Q19. 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

a) Density of metal can′t be determined

b) Metal is twice as dense as water

c) Metal will float in water

d) Metal is twice as dense as unknown fluid

Q20. The C.G. of a solid hemisphere lies on the central radius 3r

a) At distance — from the plane base 3r

b) At distance — from the plane base 3r

c) At distance — from the plane base 3r

d) At distance — from the plane base or

Part 8: Objective questions and answers of Mechanics & Strength of Materials