91. The angular speed of PQ in rev/s when the block R attains maximum speed during forward stroke (stroke with slower speed) is (in rad/s)

1. 1. 1/3

   
   
   

   2. 2/3

   
   
   

   3. 2

   
   
   

   4. 3

   
   
   

---

1. View Hint View Answer Discuss in Forum

   Maximum speed during forward stroke occur when QR & QS are perpendicular.
   V = 250 × 2 = 750 × ω_PQ
   

   ωPQ =	2	rad/sec
   	3

   Correct Option: B

   Maximum speed during forward stroke occur when QR & QS are perpendicular.
   V = 250 × 2 = 750 × ω_PQ
   

   ωPQ =	2	rad/sec
   	3

---

92. If the quick return ratio is 1: 2, then the length of the crank in mm is

1. 1. 250

   
   
   

   2. 250 √3

   
   
   

   3. 500

   
   
   

   4. 500 √3

   
   
   

---

1. View Hint View Answer Discuss in Forum

   250

   Correct Option: A

   250

---

---

93. The input link O₂P of a four bar linkage is rotated at 2 rad/s in counter clockwise direction as shown below. The angular velocity of the coupler PQ in rad/s, at an instant when ∠O₄O₂P = 180°, is
    
    PQ = Q₄Q = √2a
    O₂P = O₂O₄ = a

1. 1. 4

   
   
   

   2. 2√2

   
   
   

   3. 1

   
   
   

   4. 1√2

   
   
   

---

1. View Hint View Answer Discuss in Forum

   
   When ∠O₄O₂ P = 180°
   

   Now,	ω3	=	I12I23	=	a
   	ω2		I12I23		2a

   
   

   	ω3	=	1
   	2		2

   
   ω₃ = 1 rad/s

   Correct Option: C

   
   When ∠O₄O₂ P = 180°
   

   Now,	ω3	=	I12I23	=	a
   	ω2		I12I23		2a

   
   

   	ω3	=	1
   	2		2

   
   ω₃ = 1 rad/s

---

94. In a four-bar linkage, S denotes the shortest link length, L is the longest link length, P and Q are the lengths of other two links. At least one of the three moving links will rotate by 360° if

1. 1. S + L ≤ P + Q

   
   
   

   2. S + L > P + Q

   
   
   

   3. S + P ≤ L + Q

   
   
   

   4. S + P > L + Q

   
   
   

---

1. View Hint View Answer Discuss in Forum

   According to Grashoff’s Criteria.
   S + L ≤ P + Q

   Correct Option: A

   According to Grashoff’s Criteria.
   S + L ≤ P + Q

---

---

95. For a mechanism shown below, the mechanical advantage for the given configuration is
    

1. 1. 0.0

   
   
   

   2. 0.5

   
   
   

   3. 1.0

   
   
   

   4. ∞

   
   
   

---

1. View Hint View Answer Discuss in Forum

   Mechanical advantage =	Load (output force)
   	Effort (input force)

   
   For a four bar linkage in toggle position, effort = 0
   ∴  Mechanical Advantage = ∞

   Correct Option: A

   Mechanical advantage =	Load (output force)
   	Effort (input force)

   
   For a four bar linkage in toggle position, effort = 0
   ∴  Mechanical Advantage = ∞

---