Strength Of Materials — Part 1 MCQs with Explanations

Option A: Weight Weight is a vector quantity as it has both magnitude and direction (directed towards the center of the Earth). Option B: Velocity Velocity is a vector quantity because it represents both the speed and direction of an object. Option C: Acceleration Acceleration is also a vector quantity, as it defines the rate of change of velocity and includes direction. Option D: Force Force is a vector quantity, as it has both magnitude and direction, acting on an object to cause acceleration. Correct Explanation: While all the options might seem to have directional attributes, **Weight** is actually a vector quantity. There is no option in the given choices that represents a scalar (non-vector) quantity.

Option A: Mechanical advantage is greater than velocity ratio In an ideal machine, there are no energy losses due to friction or other resistances. Therefore, the mechanical advantage cannot be greater than the velocity ratio because that would imply the machine is creating additional energy, which is impossible in an ideal system. Option B: Mechanical advantage is equal to velocity ratio In an ideal machine , the mechanical advantage (MA) is equal to the velocity ratio (VR) because all the input energy is fully transmitted to the output without any losses. This equality holds true as there are no inefficiencies in an ideal machine. Option C: Mechanical advantage is less than velocity ratio In real machines, due to energy losses, the mechanical advantage is often less than the velocity ratio. However, in ideal machines, where no losses are assumed, the mechanical advantage should equal the velocity ratio, not be less than it. Option D: Mechanical advantage is unity While mechanical advantage can be unity in specific scenarios, it is not a general characteristic of all ideal machines. An ideal machine’s mechanical advantage will match the velocity ratio, but the value is not limited to unity. Conclusion: The correct answer is Option B: Mechanical advantage is equal to velocity ratio . In an ideal machine, mechanical advantage equals the velocity ratio due to the absence of energy losses.

Imagine you're trying to open a door with a key. You're not just pushing or pulling straight (that would be a force). Instead, you're twisting the key. This twisting action is what we call a moment in engineering. A moment is a turning effect caused by a force acting at a distance from a pivot point (in this case, the center of the lock). It's like a force trying to rotate something. So, the correct answer is a moment because it describes the turning action you apply to the key in the lock. Coplanar forces act in the same plane, which isn't what happens when you turn a key. Non-coplanar forces act in different planes, also not applicable here. A couple is two equal and opposite parallel forces, which also doesn't represent the action of turning a key.

Gravitational force of attraction towards the centre of the earth is the correct answer to “The weight of a body is due to”. This question is standard in competitive examination syllabi for Strength Of Materials.

Moment of the couple is the correct answer to “The product of either force of couple with the arm of the couple is called”. This question is standard in competitive examination syllabi for Strength Of Materials.

Density of metal can’t be determined is the correct answer to “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”. This question is standard in competitive examination syllabi for Strength Of Materials.

Bodies having relative motion is the correct answer to “Coulomb friction is the friction between”. This question is standard in competitive examination syllabi for Strength Of Materials.

Hyperbola is the correct answer to “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”. This question is standard in competitive examination syllabi for Strength Of Materials.

Newton is the correct answer to “The unit of force in S.I. units is”. This question is standard in competitive examination syllabi for Strength Of Materials.

Joule is the correct answer to “The unit of work or energy in S.I. units is”. This question is standard in competitive examination syllabi for Strength Of Materials.

Watt is the correct answer to “The unit of power in S.I. units is”. This question is standard in competitive examination syllabi for Strength Of Materials.

Right angled triangle is the correct answer to “The C.G. of a plane lamina will not be at its geometrical centre in the case of a”. This question is standard in competitive examination syllabi for Strength Of Materials.

At an angle equal to the angle of friction to the inclined plane is the correct answer to “Least force required to draw a body up the inclined plane is W sin (plane inclination + friction angle) applied in the direction”. This question is standard in competitive examination syllabi for Strength Of Materials.

Dynamic friction is the correct answer to “Frictional force encountered after commencement of motion is called”. This question is standard in competitive examination syllabi for Strength Of Materials.

20 kg, -ve sense is the correct answer to “The resultant of the following three couples 20 kg force, 0.5 m arm, +ve sense 30 kg force, 1 m arm, -ve sense 40 kg force, 0.25 m arm, +ve sense having arm of 0.5 m will be”. This question is standard in competitive examination syllabi for Strength Of Materials.

The point of application of the resultant of all the forces tending to cause a body to rotate about a certain axis is the correct answer to “Center of percussion is”. This question is standard in competitive examination syllabi for Strength Of Materials.

Produce a moment of couple is the correct answer to “Two coplanar couples having equal and opposite moments”. This question is standard in competitive examination syllabi for Strength Of Materials.

Resolution of forces is the correct answer to “The algebraic sum of the resolved parts of a number of forces in a given direction is equal to the resolved part of their resultant in the same direction. This is as per the principle of”. This question is standard in competitive examination syllabi for Strength Of Materials.

$$\sqrt 5\,$$ and $$\sqrt 5 $$ kg is the correct answer to “The magnitude of two forces, which when acting at right angle produce resultant force of $$\sqrt {10} $$ kg and when acting at 60° produce resultant of $$\sqrt {13} $$ kg. These forces are”. This question is standard in competitive examination syllabi for Strength Of Materials.

Non-equilibrium is the correct answer to “If three forces acting in different planes can be represented by a triangle, these will be in”. This question is standard in competitive examination syllabi for Strength Of Materials.

All the above are correct is the correct answer to “If three forces acting in one plane upon a rigid body, keep it in equilibrium, then they must either”. This question is standard in competitive examination syllabi for Strength Of Materials.

Three members with unknown forces of the frame is the correct answer to “In determining stresses in frames by methods of sections, the frame is divided into two parts by an imaginary section drawn in such a way as not to cut more than”. This question is standard in competitive examination syllabi for Strength Of Materials.

Acceleration is the correct answer to “Which of the following is not a scalar quantity”. This question is standard in competitive examination syllabi for Strength Of Materials.

Momentum is the correct answer to “Which of the following is a vector quantity”. This question is standard in competitive examination syllabi for Strength Of Materials.

All of the above is the correct answer to “Effect of a force on a body depends upon”. This question is standard in competitive examination syllabi for Strength Of Materials.

The friction force acting when the body is in motion is the correct answer to “Kinetic friction is the”. This question is standard in competitive examination syllabi for Strength Of Materials.

The same at every point in its line of action is the correct answer to “According to principle of transmissibility of forces, the effect of a force upon a body is”. This question is standard in competitive examination syllabi for Strength Of Materials.

At distance $$\frac{{3{\text{r}}}}{8}$$ from the plane base is the correct answer to “The centre of gravity (C.G.) of a solid hemisphere lies on the central radius”. This question is standard in competitive examination syllabi for Strength Of Materials.

Reducing the problem of kinetics to equivalent statics problem is the correct answer to “D'Alembert's principle is used for”. This question is standard in competitive examination syllabi for Strength Of Materials.

Coefficient of friction is the correct answer to “Tangent of angle of friction is equal to”. This question is standard in competitive examination syllabi for Strength Of Materials.

All of the above is the correct answer to “A force is completely defined when we specify”. This question is standard in competitive examination syllabi for Strength Of Materials.

Parabola is the correct answer to “A heavy string attached at two ends at same horizontal level and when central dip is very small approaches the following curve”. This question is standard in competitive examination syllabi for Strength Of Materials.

Parabola is the correct answer to “A cable with a uniformly distributed load per horizontal metre run will take the following shape”. This question is standard in competitive examination syllabi for Strength Of Materials.

Second order is the correct answer to “A pair of smith’s tongs is an example of the lever of”. This question is standard in competitive examination syllabi for Strength Of Materials.

Kcal/kg sec is the correct answer to “Which of the following is not the unit of power”. This question is standard in competitive examination syllabi for Strength Of Materials.

To replace them by a single force is the correct answer to “If a number of forces act simultaneously on a particle, it is possible”. This question is standard in competitive examination syllabi for Strength Of Materials.

62.5 m is the correct answer to “A body moves, from rest with a constant acceleration of 5 m per sec. The distance covered in 5 sec is most nearly”. This question is standard in competitive examination syllabi for Strength Of Materials.

Compression or tension is the correct answer to “The possible loading in various members of framed structures are”. This question is standard in competitive examination syllabi for Strength Of Materials.

Hp is the correct answer to “Which of the following is not the unit of work, energy and heat”. This question is standard in competitive examination syllabi for Strength Of Materials.

2j-3 is the correct answer to “If n = number of members andy = number of joints, then for a perfect frame, n =”. This question is standard in competitive examination syllabi for Strength Of Materials.