Questions and Answers Section 2

Questions and Answers

Question :

11.The brake commonly used in railway trains is 

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shoe brake.

Note:-When the brake is applied, the shoe moves and presses the lining against the inside of the drum. The friction between lining and drum provides the braking effort. Energy is dissipated as heat. Modern cars have disc brakes all round, or discs at the front and drums at the rear.




Question :

12.The acceleration of the particle moving with simple harmonic motion is zero at the

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mean position.

Note:-A mean position is any position that is a moderate position between two other extreme positions.

Question :

13.A system of masses rotating in different parallel planes is in dynamic balance if the

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resultant force and resultant couple are both equal to zero.

Question :

14.The radial distance from the top of a tooth to the bottom of a tooth in a meshing gear, is called

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clearance.

Note:-Gears are toothed wheels which are used to transmit force to other gears or toothed parts by meshing with minimal slip. When two gears are meshed together, the smaller gear is called a pinion. The gear transmitting force is referred to as a drive gear, and the receiving gear is called the driven gear.

In a pair of gears, backlash is the amount of clearance between mated gear teeth.

Question :

15.Bifilar suspension method is used to find the

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moment of inertia of the body.

Questions and Answers Section 1

Questions and Answers

Question :

01. In a reciprocating steam engine,which of the following forms a kinematic link?

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Crankshaft and flywheel

Note:-Each resistant body in a machine which moves relative to another resistant body is called Kinematic link or element.

Question :

02.The maximum velocity of a particle moving with simple harmonic motion is

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ωr

Note:-oscillatory motion under a retarding force proportional to the amount of displacement from an equilibrium position.

Question :

03.When the tip of a tooth undercuts the root on its mating gear, it is known as 

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interference

Note:-When two gears are in mesh at one instant there is a chance to mate involute portion with non-involute portion of mating gear. This phenomenon is known as "interference" and occurs when the number of teeth on the smaller of the two meshing gears is less than a required minimum.

Question :

04.Under logarithmic decrement, the amplitude of successive vibrations are

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in geometric progression

Question :

05.In a cone pulley, if the sum of radii of the pulleys on the driving and driven shafts is Constant, then

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crossed belt drive is recommended.

Question :

06.The tractive force is maximum or minimum when the angle of inclination of crank with the line of stroke (θ) is equal to

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90° and 180°

Note:-Traction, or tractive force, is the force used to generate motion between a body and a tangential surface, through the use of dry friction, though the use of shear force of the surface is also commonly used.

Question :

07.A point on a connecting link (excluding end points) of a double slider crank mechanism traces a

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Elliptical path

Note:-A small body in space orbits a large one (like a planet around the sun) along an elliptical path, with the large body being located at one of the ellipse foci. Two bodies with similar mass orbiting around a common barycenter with elliptic orbits.

Question :

08.According to Kennedy's theorem, if three bodies move relatively to each other, their instantaneous centres will lie on a

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straight line.




Question :

09.The periodic time is given by (where ω = Angular velocity of the particle in rad/s)

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2π/ω

Question :

10.When two links are connected by a pin joint, their instantaneous centre lies

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at the pin joint.