1. In which of the following cases Ritterhaus’ construction can be used?
a) Crank has a uniform angular velocity
b) Crank has a uniform angular acceleration
c) Lever has a uniform angular acceleration
d) When the motion is SHM
Explanation: Ritterhus’ construction can be used in both the cases, i.e when the crack has both uniform and non uniform angular velocity
2. Ritterhaus’ construction is used to determine graphically the velocity and acceleration of reciprocating parts of an IC engine
a) true
b) False
Explanation:The velocity and acceleration of the reciprocating parts of the steam engine or internal combustion engine may be determined by the graphical method or analytical method, Ritterhaus’ construction provides graphical solution
3. Which of the following construction methods is not used to calculate the velocity and acceleration of reciprocating parts of the internal combustion engine?
a) Klien’s construction
b)Ritterhaus’s construction
c) Bennett’s construction
d) D-Alembert’s constructions
Explanation: D-Alembert’s principle is used to convert a dynamic mechanic problem to a static problem with the help of inertia forces while the other three constructions are used to determine the velocity and acceleration of reciprocating parts of IC engine.
4. If OC is the crank and PC is the connecting rod rotating in clockwise direction in the figure given below, then triangle OCM is known as _________
a) Klein’s velocity diagram
b) Klein’s acceleration diagram
c) Bennett’ velocity diagram
d) Bennett’ acceleration diagram
Explanation:Since the crank is rotating in the clockwise direction, then the velocity of C will be perpendicular to OC and it’s value is given by w2.OC, hence triangle OCM forms a velocity polygon
5. Bennett’ construction is used when the motion of the crank is linear cycloidal.
a) True
b) False
Explanation: Bennett’ construction is used when the crank is undergoing a motion which has uniform angular velocity
6. Acceleration of any point D on the connecting rod is given by ________
a) ω2.OD1
b) ω2.OD2
c) ω2.OD
d) ω2.PD
Explanation: Acceleration at D is the vector sum of radial acceleration and tangential acceleration components. Hence the net acceleration is ω2.OD2.
7. In which of the following cases Bennett’s construction can be used
a) Crank has a uniform angular velocity
b) Crank has a uniform angular acceleration
c) Lever has a uniform angular acceleration
d) When the motion is SHM
Explanation: Bennett’s construction can be used in both the cases, i.e when the crack has both uniform and non uniform angular velocity.
8. Bennett’ construction is used to determine graphically the velocity and acceleration of reciprocating parts of an IC engine
a) True
b) False
Explanation: The velocity and acceleration of the reciprocating parts of the steam engine or internal combustion engine are determined by either graphical method or analytical method, Bennett’s construction provides graphical solution for the same
9. Velocity of any point D on the connecting rod is given by ________
a) ω.OD1
b) ω.OD2
c) ω.OD
d) ω.PD
Explanation: Linear velocity is obtained by a product of angular velocity of the crank and the perpendicular distance of the respective point. In this case ω is the angular velocity and OD1 is the perpendicular distance.
10. If the crank and the connecting rod are 300 mm and 1 m long respectively and the crank rotates at a constant speed of 250 r.p.m., determine the crank angle at which the maximum velocity occurs is ____
a) 45
b) 75
c) 90
d) 60
Explanation: For maximum velocity of the piston : cosθ + 2cos(2θ)/2n = 0
n = l/r : 1/.3 = 3.33
therefore, θ = 75°