Skip to main content

ISRO 2014 Mechanical Engineering Questions, Answers and Explanation

ISRO 2014 Mechanical Engineering Questions, Answers and Explanation

18. Tension in the cable supporting a lift of weight 'W' and having an acceleration 'a' while going upward is (g is acceleration due to gravity)
a) W(1+a/g)
b) W(1-a/g)
c) W(2+a/g)
d) W(1+2a/g)

Answer
a) W(1+a/g)

Explanation [Engineering Mechanics]
Tension increases when the lift accelerate upwards and decreases when the lift accelerate downwards.
Mass of the lift = W/g
Increase in tension due to acceleration = mass of list * acceleration of lift = W/g*a
Total tension = Tension due to gravity + Tension due to acceleration
 = W + W/g*a = W(1+g/a)

2014. 80. Which type of gear meshing should be employed to transmit torque to a linear force?
a) Epicyclic gear
b) Helical gear
c) Bevel gear
d) Rack and pinion
Answer
d) Rack and pinion
Explanation [Theory of Machines and Mechanical Vibrations]
Epicyclic gear trains have one or more axes of gears in motion. In all other gear types the gear rotates about an axis but the axis does not move.
Helical gears are smoother in operations and create a thrust load and hence required support to compensate this load. They can also be used to transmit torques at 90o 
Bevel gears are the ones in which the axes of gears intersect normally at 90o. But they can work at other angles also.
Rack and pinion gears are used to convert rotation into linear motion.


Popular posts from this blog

ISRO Mechanical Engineering Fluid Mechanics Questions, Answers and Explanation

ISRO Mechanical Engineering Fluid Mechanics Fluid Properties - Bulk modulus 2011. 10.  A liquid compressed in cylinder has a volume of 0.04 m 3  at 50kg/cm 2  and a volume of 0.039 m 3  at 150 kg/cm 2 . The bulk modulus of elasticity of liquid is a) 400 kg/cm 2 b) 40 x 10 6  kg/cm 2 c) 40 x 10 5  kg/cm 2 d) 4000 kg/cm 2 Answer d) 4000 kg/cm 2 Explanation The bulk elastic properties of a material determine how much it will compress under a given amount of external pressure. The ratio of the change in pressure to the fractional volume compression is called the bulk modulus of the material. The reciprocal of the bulk modulus is called the compressibility of the substance. Bulk Modulus, B = ΔP/(ΔV/V) Here ΔP = 150-50 =100 kg/cm 2 ΔV = 0.04-0.039 = 0.001m 3 V = 0.04m 3 B = (100/(0.001/0.04)) = 100x0.04/0.001 =  4000 kg/cm 2 Fluid Properties - Surface Tension 2011.13  If the surface tension of water-air interface ...
Read more

The Da Vinci Code trip

Chapter I of the novel begins with Robert Langdon asleep in the Ritz Hotel. Our trip begins with ourselves just outside the Ritz Hotel. One of the posh hotels with a lot of high end luxury cars parked outside. Ritz Hotel, Paris Sitting up now, Langdon frowned at his bedside Guest Relations Handbook, whose cover boasted:     SLEEP LIKE A BABY IN THE CITY OF LIGHTS. SLUMBER AT THE PARIS RITZ. In the beginning on his way to Louvre - The crisp April air whipped through the open window of the Citroën ZX as it skimmed south past the Opera House and crossed Place Vendôme . As the Citroën accelerated southward across the city, the illuminated profile of the Eiffel Tower appeared, shooting skyward in the distance to the right. Symbologists often remarked that France—a country renowned for machismo, womanizing, and diminutive insecure leaders like Napoleon and Pepin the Short—could not have chosen a more apt national emblem than a thous...
Read more

ISRO Mechanical Engineering/Refrigeration and Air Conditioning Thermal Engineering Questions, Answers and Explanation

ISRO Mechanical Engineering Thermal Engineering Questions, Answers and Explanation System Properties 2007.2.  The universal gas constant of a gas is the product of molecular weight of the gas and a) Gas constant b) Specific heat at constant pressure c) Specific heat at constant volume d) None of the above Answer a) Gas constant Explanation The value of universal gas constant is 8.314 J mol -1 K -1 . This when divided by the molecular weight of gas we get specific gas constant Molecular mass of air = 28.97 g/mol R air  = 8.314x1000/28.97 J kg -1 K -1  = 287  J kg -1 K -1 . 2007.3.  Van der Waal's equation of state of a gas is a) pV = nRT b) (p+a/V 2,/sup>)(v+b) = RT c) (p+a/V 2,/sup>)(v-b) = RT d) (p-a/V 2,/sup>)(v-b) = RT Answer c) (p+a/V 2,/sup>)(v-b) = RT Explanation The constant 'a' provides correction for inter molecular forces and b for finite molecular size.  The effect of the finite volume of the particl...
Read more