27 real Theory of Machines questions from the Mechanical Core bank, as asked in Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd — free to start.
1. What is Grubler's criterion?
Junior
A.a four-bar linkage has a fully rotating link only if the sum of the shortest and longest links does not exceed the sum of the other two
B.contact between the involute of one gear and the non-involute flank below the base circle of its mate, avoided by keeping at least 17 teeth on a 20° full-depth pinion
C.governor whose equilibrium speed is identical at every sleeve position, giving infinite sensitivity and unstable hunting
D.mobility of a planar mechanism equals 3(n − 1) − 2j − h, where n is links, j lower pairs and h higher pairs
A.Grubler's criterion — mobility of a planar mechanism equals 3(n − 1) − 2j − h, where n is links, j lower pairs and h higher pairs
B.Grubler's criterion — reactive torque Iωωp produced when the spin axis of a rotor is forced to precess, felt by ships pitching, aircraft turning and two-wheelers cornering
C.Grubler's criterion — third derivative of follower displacement, finite for cycloidal motion but infinite for simple harmonic motion at the dwell junction, so cycloidal is chosen for high speed
D.Grubler's criterion — rotational speed at which centrifugal force from eccentricity balances the shaft's elastic restoring force, coinciding with its natural transverse frequency
A.reactive torque Iωωp produced when the spin axis of a rotor is forced to precess, felt by ships pitching, aircraft turning and two-wheelers cornering
B.a four-bar linkage has a fully rotating link only if the sum of the shortest and longest links does not exceed the sum of the other two
C.mobility of a planar mechanism equals 3(n − 1) − 2j − h, where n is links, j lower pairs and h higher pairs
D.ratio of the difference between maximum and minimum shaft speeds to mean speed, the quantity a flywheel is sized to limit
5. Which term means: "a four-bar linkage has a fully rotating link only if the sum of the shortest and longest links does not exceed the sum of the other two"?
A.Grashof's law — mobility of a planar mechanism equals 3(n − 1) − 2j − h, where n is links, j lower pairs and h higher pairs
B.Grashof's law — a four-bar linkage has a fully rotating link only if the sum of the shortest and longest links does not exceed the sum of the other two
C.Grashof's law — ratio of the difference between maximum and minimum shaft speeds to mean speed, the quantity a flywheel is sized to limit
D.Grashof's law — reactive torque Iωωp produced when the spin axis of a rotor is forced to precess, felt by ships pitching, aircraft turning and two-wheelers cornering
A.governor whose equilibrium speed is identical at every sleeve position, giving infinite sensitivity and unstable hunting
B.a four-bar linkage has a fully rotating link only if the sum of the shortest and longest links does not exceed the sum of the other two
C.contact between the involute of one gear and the non-involute flank below the base circle of its mate, avoided by keeping at least 17 teeth on a 20° full-depth pinion
D.mobility of a planar mechanism equals 3(n − 1) − 2j − h, where n is links, j lower pairs and h higher pairs
8. Which term means: "contact between the involute of one gear and the non-involute flank below the base circle of its mate, avoided by keeping at least 17 teeth on a 20° full-depth pinion"?
A.Gear interference — reactive torque Iωωp produced when the spin axis of a rotor is forced to precess, felt by ships pitching, aircraft turning and two-wheelers cornering
B.Gear interference — rotational speed at which centrifugal force from eccentricity balances the shaft's elastic restoring force, coinciding with its natural transverse frequency
C.Gear interference — third derivative of follower displacement, finite for cycloidal motion but infinite for simple harmonic motion at the dwell junction, so cycloidal is chosen for high speed
D.Gear interference — contact between the involute of one gear and the non-involute flank below the base circle of its mate, avoided by keeping at least 17 teeth on a 20° full-depth pinion
A.Coriolis acceleration — reactive torque Iωωp produced when the spin axis of a rotor is forced to precess, felt by ships pitching, aircraft turning and two-wheelers cornering
B.Coriolis acceleration — component 2Vω that appears when a slider moves along a rotating link, directed perpendicular to the sliding velocity
C.Coriolis acceleration — rotational speed at which centrifugal force from eccentricity balances the shaft's elastic restoring force, coinciding with its natural transverse frequency
D.Coriolis acceleration — contact between the involute of one gear and the non-involute flank below the base circle of its mate, avoided by keeping at least 17 teeth on a 20° full-depth pinion
A.a four-bar linkage has a fully rotating link only if the sum of the shortest and longest links does not exceed the sum of the other two
B.component 2Vω that appears when a slider moves along a rotating link, directed perpendicular to the sliding velocity
C.third derivative of follower displacement, finite for cycloidal motion but infinite for simple harmonic motion at the dwell junction, so cycloidal is chosen for high speed
D.contact between the involute of one gear and the non-involute flank below the base circle of its mate, avoided by keeping at least 17 teeth on a 20° full-depth pinion
14. Which term means: "third derivative of follower displacement, finite for cycloidal motion but infinite for simple harmonic motion at the dwell junction, so cycloidal is chosen for high speed"?
A.Cam jerk — rotational speed at which centrifugal force from eccentricity balances the shaft's elastic restoring force, coinciding with its natural transverse frequency
B.Cam jerk — ratio of the difference between maximum and minimum shaft speeds to mean speed, the quantity a flywheel is sized to limit
C.Cam jerk — third derivative of follower displacement, finite for cycloidal motion but infinite for simple harmonic motion at the dwell junction, so cycloidal is chosen for high speed
D.Cam jerk — governor whose equilibrium speed is identical at every sleeve position, giving infinite sensitivity and unstable hunting
A.ratio of the difference between maximum and minimum shaft speeds to mean speed, the quantity a flywheel is sized to limit
B.component 2Vω that appears when a slider moves along a rotating link, directed perpendicular to the sliding velocity
C.reactive torque Iωωp produced when the spin axis of a rotor is forced to precess, felt by ships pitching, aircraft turning and two-wheelers cornering
D.governor whose equilibrium speed is identical at every sleeve position, giving infinite sensitivity and unstable hunting
A.Coefficient of fluctuation of speed — ratio of the difference between maximum and minimum shaft speeds to mean speed, the quantity a flywheel is sized to limit
B.Coefficient of fluctuation of speed — component 2Vω that appears when a slider moves along a rotating link, directed perpendicular to the sliding velocity
C.Coefficient of fluctuation of speed — third derivative of follower displacement, finite for cycloidal motion but infinite for simple harmonic motion at the dwell junction, so cycloidal is chosen for high speed
D.Coefficient of fluctuation of speed — governor whose equilibrium speed is identical at every sleeve position, giving infinite sensitivity and unstable hunting
A.component 2Vω that appears when a slider moves along a rotating link, directed perpendicular to the sliding velocity
B.third derivative of follower displacement, finite for cycloidal motion but infinite for simple harmonic motion at the dwell junction, so cycloidal is chosen for high speed
C.governor whose equilibrium speed is identical at every sleeve position, giving infinite sensitivity and unstable hunting
D.rotational speed at which centrifugal force from eccentricity balances the shaft's elastic restoring force, coinciding with its natural transverse frequency
A.Isochronous governor — contact between the involute of one gear and the non-involute flank below the base circle of its mate, avoided by keeping at least 17 teeth on a 20° full-depth pinion
B.Isochronous governor — third derivative of follower displacement, finite for cycloidal motion but infinite for simple harmonic motion at the dwell junction, so cycloidal is chosen for high speed
C.Isochronous governor — rotational speed at which centrifugal force from eccentricity balances the shaft's elastic restoring force, coinciding with its natural transverse frequency
D.Isochronous governor — governor whose equilibrium speed is identical at every sleeve position, giving infinite sensitivity and unstable hunting
A.rotational speed at which centrifugal force from eccentricity balances the shaft's elastic restoring force, coinciding with its natural transverse frequency
B.reactive torque Iωωp produced when the spin axis of a rotor is forced to precess, felt by ships pitching, aircraft turning and two-wheelers cornering
C.third derivative of follower displacement, finite for cycloidal motion but infinite for simple harmonic motion at the dwell junction, so cycloidal is chosen for high speed
D.contact between the involute of one gear and the non-involute flank below the base circle of its mate, avoided by keeping at least 17 teeth on a 20° full-depth pinion
23. Which term means: "rotational speed at which centrifugal force from eccentricity balances the shaft's elastic restoring force, coinciding with its natural transverse frequency"?
A.Whirling speed of a shaft — component 2Vω that appears when a slider moves along a rotating link, directed perpendicular to the sliding velocity
B.Whirling speed of a shaft — a four-bar linkage has a fully rotating link only if the sum of the shortest and longest links does not exceed the sum of the other two
C.Whirling speed of a shaft — rotational speed at which centrifugal force from eccentricity balances the shaft's elastic restoring force, coinciding with its natural transverse frequency
D.Whirling speed of a shaft — third derivative of follower displacement, finite for cycloidal motion but infinite for simple harmonic motion at the dwell junction, so cycloidal is chosen for high speed
A.reactive torque Iωωp produced when the spin axis of a rotor is forced to precess, felt by ships pitching, aircraft turning and two-wheelers cornering
B.component 2Vω that appears when a slider moves along a rotating link, directed perpendicular to the sliding velocity
C.rotational speed at which centrifugal force from eccentricity balances the shaft's elastic restoring force, coinciding with its natural transverse frequency
D.a four-bar linkage has a fully rotating link only if the sum of the shortest and longest links does not exceed the sum of the other two
26. Which term means: "reactive torque Iωωp produced when the spin axis of a rotor is forced to precess, felt by ships pitching, aircraft turning and two-wheelers cornering"?
A.Gyroscopic couple — mobility of a planar mechanism equals 3(n − 1) − 2j − h, where n is links, j lower pairs and h higher pairs
B.Gyroscopic couple — reactive torque Iωωp produced when the spin axis of a rotor is forced to precess, felt by ships pitching, aircraft turning and two-wheelers cornering
C.Gyroscopic couple — contact between the involute of one gear and the non-involute flank below the base circle of its mate, avoided by keeping at least 17 teeth on a 20° full-depth pinion
D.Gyroscopic couple — ratio of the difference between maximum and minimum shaft speeds to mean speed, the quantity a flywheel is sized to limit
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