Theory of Machine MCQ Quiz

In a multi-plate clutch, the number of discs on the driving shaft is indeed given by n1. This means that the driving shaft of the clutch is equipped with n1 discs. The presence of multiple discs allows for increased surface area and friction, which enhances the clutch's ability to transmit torque efficiently. Therefore, the statement is true.

If the shortest link in a mechanism is fixed, it means that it cannot move or rotate. In a double crank mechanism, both the shortest links are connected to cranks, which are rotating arms. When one crank rotates, it causes the other crank to rotate as well. Therefore, if the shortest link is fixed, it implies that both cranks are fixed and cannot rotate. Hence, the correct answer is Double crank mechanism.

A planar mechanism is a mechanism in which the relative motions of the rigid bodies are in one plane or in parallel planes. This means that the movement of the components of the mechanism occurs only in a two-dimensional space, making it easier to analyze and design. In contrast, a spatial mechanism allows for movement in three-dimensional space, a spherical mechanism allows for movement along curved surfaces, and a flexure mechanism uses elastic elements for motion. Therefore, the correct answer is planar mechanism.

If the opposite links of a four-bar linkage are equal in length, it means that the two pairs of opposite sides are of the same length. In a parallelogram, opposite sides are parallel and equal in length. Therefore, if the opposite links of a four-bar linkage are equal, the links will always form a parallelogram.

A link serves multiple purposes. It can act as a support, providing stability and strength to a structure. It can also guide other links, directing their movement or positioning. Additionally, a link can transmit motion, allowing for the transfer of force or energy from one component to another. Therefore, the correct answer is "All of the above."

The given typewriter mechanism has 7 binary joints and 6 links, which means that it satisfies the Gruebler's criterion for mobility. This criterion states that for a mechanism to be kinematically sound, the number of degrees of freedom (given by 3n - 2j - h) should be greater than or equal to zero, where n is the number of links, j is the number of binary joints, and h is the number of higher pairs. In this case, the mechanism has 6 degrees of freedom (3(6) - 2(7) - 0 = 6), which is greater than zero. Therefore, the mechanism is kinematically sound.

The size of the cam depends upon the base circle. The base circle is the theoretical circle from which the cam profile is generated. It is the circle that the pitch circle rolls on without slipping. The size of the base circle determines the overall dimensions and shape of the cam, and is crucial in determining the motion and performance of the cam mechanism.

Bevel gears are equivalent to rolling cones because they have a conical shape that allows them to mesh together at an angle. This design enables the transmission of rotational motion between intersecting shafts, particularly when the shafts are not parallel. The conical shape of bevel gears allows for smooth and efficient power transfer, making them suitable for applications where torque needs to be transmitted at an angle.

The working depth of the gear and the pinion of the bevel gears is 2 m and 0.7 m respectively.

Watt's mechanism is approximately a straight-line motion mechanism. This mechanism uses a combination of linkages and gears to convert rotary motion into linear motion along a straight line. It is commonly used in applications such as steam engines and pumps. The other mechanisms mentioned, Scott Russell's mechanism, Peaucellier mechanism, and Hart's mechanism, do not primarily produce straight-line motion.

The contact ratio is the ratio of the angle of action to the pitch angle. It represents the extent to which two gears are in contact with each other during their rotation. A higher contact ratio indicates a smoother and more efficient gear operation, while a lower contact ratio can lead to increased noise and wear. Therefore, the contact ratio is an important factor to consider when designing gears to ensure their proper functioning.

Cylindrical is not a type of clutch. The other options listed are all types of clutches commonly used in various mechanical systems. Centrifugal clutches are used in machines such as lawn mowers, where the clutch engages as the engine speed increases. Single disc clutches are commonly used in automobiles, where a single friction disc is pressed against a flywheel to transmit power. Conical clutches are used in heavy machinery and vehicles, where conical surfaces are pressed together to transmit power. However, there is no known type of clutch called a cylindrical clutch.

Incompletely constrained motion refers to the motion between a pair that occurs in more than one direction. This means that the pair is not fully restricted or limited to only one specific direction of motion. Instead, it has the freedom to move in multiple directions, allowing for a greater range of motion.

Bevel gears have the highest contact ratio among the given options. Bevel gears are used to transmit motion between intersecting axes, and they have teeth that are cut on a conical surface. The contact ratio refers to the number of teeth in contact at any given moment, and bevel gears have a higher number of teeth in contact compared to other types of gears. This increased contact ratio enhances the load-bearing capacity and efficiency of the gears, making them suitable for applications that require high torque transmission.

A rotary internal combustion engine typically has 7 cylinders. This type of engine, also known as a Wankel engine, features a unique design that uses a triangular rotor instead of pistons. The rotor rotates within an oval-shaped housing, creating compression and combustion in each of the three chambers. As the rotor completes three revolutions for every combustion cycle, it effectively produces the equivalent of 7 cylinders. This design allows for a compact and lightweight engine with high power output and smooth operation.