QUESTION PAPER 7

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1.a) Explain the angular momentum. A rocket burns 0.25 kg of fuel per second and ejects it as a
gas with the velocity of 15 km/s. calculate the force exerted by the ejected gas on the rocket.
Express the value in newton’s. (7)
b) Define mechanical advantage, Velocity ratio and efficiency as applied to machines. (7)
2. a) In a wheel and axel arrangement, the radius of the wheel is 30 cm and the radius of the axel
is 2 cm. To overcome a resistance of 48 kg wt an effort of 6 kg wt has to be applied Calculate
the mechanical advantage, velocity ration and efficiency of the arrangement. (7)
b) Explain the term “Gyro inertia” and “gyroscopic motion”. (7)
3. a) Define Relative velocity. A man is walking due to east at the rate of 2 km/hr.Rain appears to
him to fall down vertically at the rate of 2km/hr. Find the actua velocity and direction of the
rainfall. (7)
b) Explain the following on the basis of Pascal’s law: (7)
i. Hydraulic brake ii Hydraulic lift
4. a) Explain the following with reference to Bernoulli’s theorem: (7)
i.Venturimeter ii.Bunsen burner
b) Explain the term ‘meta centre’ and ‘centre of buoyancy’. Why should the meta centre lie
above the CG of the floating body. (7)
5. a) Define surface tension? Derive an expression for the excess pressure inside the soap bubble of radius R. (7)
b) Calculate the horizontal force required to move a plate of area 100 sq cm with a velocity of
4.5 cm/s when it rests on a layer of oil 1.5mm thick, η= 20 poise. (7)
6. a) What is Reynolds number? How is it related with critical velocity. (7)
b) What do you understand by the term elasticity? Define stress, normal stress, tangential stress
and strain. (7)
7. a) Discuss anomalous expansion of water. (7)
b) What are the different modes of transmission of heat? Give two example of each. (7)
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