SOLUTIONS RATED A+
✔✔Four links are connected as indicated in the following figure: With the relative link
lengths shown, decide if the following statements are true or false:
(i) When link 4 rotates in a circular path, link 1 rotates in a circular path.
(ii) If link 4 is made the same length as link 1 then when link 4 rotates, link 1 can only
oscillate back-and-forth and not completely rotate. - ✔✔f f
✔✔Which of the following belts can be used in reversing drives? - ✔✔round
✔✔In the quick-return mechanism the time taken for travel in return stroke is
..................... forward stroke. - ✔✔less than
✔✔A ball bearing is required to withstand both radial loads and axial loads. The
optimum bearing from the following is: - ✔✔angular contact
✔✔A compound gear train consists of the final driven wheel with 15 teeth which meshes
with a second wheel with 90 teeth. On the same shaft as the second wheel is a wheel
with 15 teeth. This meshes with a fourth wheel, the first driver, with 60 teeth. What is the
overall gear ratio? - ✔✔0.0417
✔✔def of object in free space - ✔✔6
✔✔Which of the following statements is not true about chains? - ✔✔They are more
quiet than timing belts.
✔✔A_______ bearing supports the load acting along the axis of the shaft. - ✔✔thrust
✔✔What motor would you use in an application where constant speed is required
regardless of the load? - ✔✔shunt wound
✔✔For a long-stroke application you will use a solenoid with: - ✔✔conical armature
✔✔In a shunt-wound motor: - ✔✔armature and field coils are in parallel
✔✔Which of the following statements is not true about the three-phase synchronous
motor? - ✔✔They are self-starting.
✔✔For a thyristor:
(i) When it is switched on and forward breakdown occurs, the thyristor resistance drops
to a low value.
, (ii) The voltage at which a thyristor is switched on is determined by the current entering
the gate.
Which option BEST describes the two statements? - ✔✔t f
✔✔The brushless permanent magnet DC motor has - ✔✔a permanent magnet rotor and
a sequence of stator coils
✔✔Which of the following statements about motors is not true? - ✔✔Single-phase
motors are used for high-power requirements.
✔✔Which of the following statements is not true about brushless motors? - ✔✔high
maintenance
✔✔A stepper motor is specified as having a step angle of 6º. This means that:
(i) Each pulse input to the motor rotates the motor shaft by 6º.
(ii) An input of 300 pulses per second will cause it to rotate at 5 rev/s.
Which option BEST describes the two statements? - ✔✔t t
✔✔For a series wound DC motor:
(i) The direction of rotation of its shaft can be reversed by reversing the polarity of the
voltage supplied to the motor (i.e. the direction of the current).
(ii) The speed of rotation of the motor shaft can be controlled by varying the size of the
current supplied to the motor. - ✔✔f t
✔✔ Analog signal are signals that are: - ✔✔Continuous functions of time
✔✔Embedded systems are: - ✔✔machines with micro controllers embedded into them
✔✔The following picture is best defined as a: - ✔✔system with feedback control
✔✔Which of the following is not a typical attribute of open-loop control systems. -
✔✔Relatively accurate in matching actual to required values
✔✔box\block diagrams represent the behavior of a real system by mathematical
equations and are often described by a differential equation. - ✔✔True
✔✔The term ........ is used for the element of a correction unit that provides the power to
carry out the control action. - ✔✔actuator
✔✔A DAC is the device that converts - ✔✔a digital signal into an analog signal.
✔✔In a flow chart, Input/Output Operations: - ✔✔Are represented by parallelograms;
indicate an input or output operation.