E NGINEERING M ECHANICS Q UIZ

Question - 1 If the resultant of the given force system is a couple, the magnitude of force P is (a) 10 N (b) 10√5 (c) 20 (d) 10√2

Answer - 1 (b) 10√5

Question - 2 ‘A’ says that two forces will be in equilibrium only if they are equal in magnitude and opposite in direction. ‘B’ says that concurrent coplanar force system can be obtained by removing one or more forces from any non-concurrent force system. Who is right? (a) Only ‘A’ (b) Only ‘B’ (c) Both ‘A’ and ‘B’(d) Neither ‘A’ nor ‘B’

Answer - 2 (b) Only ‘B’

Question - 3 The FBD of the Light rod BC shown in figure is given by (b) (c) (d) (a)

Answer - 3 (c)

Question - 4 ‘ A’ says that a force cannot be resolved into three coplanar components acting in three directions. ‘B’ says that if three forces, P, Q, R [P>Q>R] acting at a point are in equilibrium, then P must be less than or equal to (Q+R). Who is correct? (a) Only ‘A’ (b) Only ‘B’ (c) Both ‘A’ and ‘B’ (d) Neither ‘A’ nor ‘B’

Answer – 4 (b) Only ‘B’

Question - 5 In a system of non-concurrent coplanar forces the three equations of equilibrium can be represented as (a) ΣX = 0 ; ΣY = 0 ; ΣM = 0 (b) ΣX = 0 ; ΣM A = 0 ; ΣM B = 0 (line AB is NOT perpendicular to direction X) (c) ΣM A = 0 ; ΣM B = 0 ; ΣM C = 0 (A,B,C are NOT collinear) (d) All the above

Answer – 5 (d) All the above

Question - 6 The moment of a force about any point is numerically equal to ____ times the area of the triangle whose base is the line representing the force; and vertex is the point about which moment is taken. (a) ½ (b) 1 (c) 2 (d) 3

Answer – 6 (c) 2

Question - 7 The SFD of a simple supported symmetrically loaded beam is given in the figure. The maximum BM will be ____________KN-m.

Answer – 7 10 KN - m

Question - 8 The truss shown in the figure is (a) deficient (b) perfect (c) redundant –(with first degree) (d) redundant - (with second degree) truss

Answer – 8 (b) perfect

Question - 9 A beam ABCD is loaded such that B.M. at ‘C’ is equal to zero. The beam is cut at ‘C’ and then the two parts of the beam are connected by a hinge at ‘C’. If the same load is now applied on the beam, then (a) SFD will not change (b) BMD will not change (c) both SFD & BMD will not change (d) the beam will collapse under the load

Answer – 9 (c) both SFD & BMD will not change

Question - 10 The value of maximum bending moment in the beam AB shown in the figure will be _______ KN- m.

Answer – KN - m

Question - 11 Consider the beam AB. The magnitude of couple M required to be applied such that the shear force and bending moment –(both)- at point A are zero, will be ______ KN- m.

Answer – 11 M = 3 KN - m

Question - 12 The number of zero-force members in the truss shown in the figure will be (a) 2 (b) 3 (c) 4 (d) 5.

Answer – 12 (d) 5.

Question - 13 The figure shows a rectangular section ABCD size 2 cm x 4 cm. Out of moments of inertia I x, I y, I AB, I AD the following will have Least value. (a) I x (b) I y (c) I AB (d) I AD

Answer - 13 (b) I y

Question - 14 A circular hole of diameter 10 cm is cut in the circular plate of radius 10 cm. The point which approximately represents the location of the cut – circle is (a) A (b) O (c) C (d) B

Answer - 14 (a) A

Question - 15 In a bending moment diagram, sudden drop in its value (vertical line) at any section indicates that (a) a couple is acting at that section (b) the shear force is zero at that section (c) the shear force is maximum at that section (d) the point of contraflexure lies at that section

Answer – 15 (a) a couple is acting at that section

Question - 16 In the bending moment diagram of a beam, if the bending moment at any point (section) is zero, then (a) the shear force at that point will be maximum (b) the load at that point must be zero (c) that point is called point of contraflexure (d) none of these

Answer - 16 (c) that point is called point of contraflexure

Question - 17 ‘A’ says that a redundant truss cannot be completely analyzed using method of joints alone. ‘B’ says that external load on a truss must be applied only at the pin joints and not between the joints. Who is correct? (a) only A (b) only B (c) both A and B(d) neither A nor B

Answer – 17 (c) both A and B

Question - 18 ‘ A’ says that while applying the parallel axis theorem between two parallel axes, one of the two axes must be a centroidal axis. ‘B’ says that the polar moment of inertia about the center of a circle is two times the moment of inertia about its diameter. Who is correct? (a) only A (b) only B (c) both A and B(d) neither A nor B

Answer – 18 (c) both A and B

Question - 19 ‘A’ says that if the density of a body is not uniform throughout, then the center of mass will not coincide with the center of gravity of the body. ‘B’ says that the centroid of a body is a geometric property, and it does not depend on the manner in which the density varies within the body. Who is correct? (a) only A(b) only B (c) both A and B (d) neither A nor B

Answer – 19 (b) only B

Question - 20 ‘A’ says that while applying method of sections, we cannot take a section which cuts more than three members of the truss. ‘B’ says that method of joints is based on the equilibrium of coplanar non-concurrent force system. Who is correct? (a) only A (b) only B (c) both A and B (d) neither A nor B

Answer - 20 (d) neither A nor B

Question - 21 Consider a cantilever beam carrying a uniformly distributed load throughout its length and a concentrated load at the free end. Find which of the following statements related to shear force (F) and bending moment (M) at the free end is TRUE. (a) Both F and M are zero (b) Both F and M are non-zero (c) F is zero, but M is non-zero (d) F is non-zero but M is zero

Answer – 21 (d) F is non-zero but M is zero

Question - 22 Find horizontal reaction at A

Answer – 22 H A = 1500 N

Question - 23 In a system of three non- concurrent coplanar forces, the three forces can be represented by the sides of a triangle taken in order. Then their resultant will be (a) zero (b) a force and a couple (c) a force (d) a couple.

Answer – 23 (d) a couple.

Question - 24 A beam AB of length 2L carries a central load P and is hinge-supported at A and B on two cantilevers. The correct value of BM at A will be _________.

Answer – 24 Zero

Question – 25 Match List-I (a, b, c, d) with List-II (1, 2, 3, 4) List-I (a)Two forces acting on a body, moving with a uniform velocity (b) A moving particle (c)Two coplanar parallel forces equal in magnitude and opposite in direction acting on a body (d) Two unequal forces acting on a body List-II (1) Kinetic energy (2) Couple (3) Forces in equilibrium (4) cause acceleration

Answer – 25 A – 3 B – 1 C – 2 D - 4

Question - 26 The resultant of given parallel force system is a single force of magnitude 10 N passing through the point (a) A (b) B (c ) C (d) none of these

Answer – 26 (b) B

Question - 27 Replace the given force system by a single force at ‘A’ and a couple.

Answer - 27 F = 300 N (right) M = N –cm ( clockwise )

Question - 28 Find ‘T’ so that the integral pulley is in equilibrium.

Answer – 28 T = 60 N

Question - 29 The reaction at point ‘B’ will be greatest in case no. _________. (No calculations needed)

Answer – 29 (c)

Question - 30 In the beam shown in the Figure, find Reaction at B.

Answer – 30 R B = 17.1 KN

Question - 31 Find resultant of the force system shown in figure

Answer – 31 Couple 120 N – m ( counter clockwise )

Question - 32 Find WRONG statement out of the following : (a)Coefficient of friction is the ratio of limiting force of friction to the weight of the body (b)Coefficient of friction depends on the materials of the bodies in contact (c)Angle of friction is the angle between normal reaction and total resultant reaction. (d)For a body resting on an inclined plane, the angle of repose will be greater than the angle of inclination of the plane.

Answer - 32 (a)Coefficient of friction is the ratio of limiting force of friction to the weight of the body

Question - 33 Consider the following statements : Assertion (A): The resultant of UDL is a single concentrated load having magnitude equal to the area under load diagram. Reason ( R ) : The line of action of the resultant force passes through the centroid of the area under load diagram. Select your answer using the codes given below : (a) both A and R are true and R is the correct explanation of A. (b) both A and R are true and R is not correct explanation of A (c ) A is true but R is false. (d) A is false but R is true.

Answer - 33 (b) both A and R are true and R is not correct explanation of A

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