ASSIGNMENT
THERMODYNAMICS AND GRAVITATION
1. The speed of revolution of an artificial satellite revolving close to the surface of earth is 8 km/s.
what will be the escape velocity of the body on the earth?
2. If the radius of earth shrinks by 1%, its mass remaining the same by what %age will be the
acceleration due to gravity on its surface change?
3. Define the term gravitational potential. Is it scalar or vector? give units and dimensions of
gravitational potential.
4. The mass and diameter of a planet are twice as that of earth. What will be the time period of
the pendulum on this planet, which is a second’s pendulum on the earth?
5. Assuming the earth to be a sphere of uniform mass density, how much would a body weigh half
way down to the center of earth if it weighed 250 N on the surface?
6. Define gravitational potential energy. Obtain expression for it.
7. Define acceleration due to gravity. Show that the value of ‘g’ decrease with increase in height ‘h’
above the surface of earth.
8. What is meant by gravitational field strength? Which of the planet of solar system has the
greatest gravitational field strength?
What is the gravitational field strength of a planet where the weight of a 60 kg astronaut is 300
N?
9. What are geostationary satellites? Calculate the height of the orbit of a satellite which appear
stationary from the surface of earth.
10. State kepler’s laws of planetary motion. Deduce newtons law of gravitation from kepler’s laws.
11. What is escape velocity? Obtain expression for escape velocity on earth. Why is it that there is
no atmosphere on the moon? Explain.
12. Define orbital velocity and derive expression for it. Calculate the orbital velocity for an artificial
satellite of earth orbiting at a height of 1000km.
THERMODYNAMICS
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What is the specific heat of a gas in (i) an isothermal process (ii) adiabatic process?
What is adiabatic process? Give two conditions for adiabatic process to take place.
Define Zeroth law in thermodynamics. What is its significance?
Define two principle specific heats of a gas. Which one is greater and why ? derive the relation
between the two.
5. Show analytically that the work done by one mole of an ideal gas during isothermal expansion
from volume V1 to V2 is given by W = RT loge V2/V1.
6. State mathematically first law of thermodynamics and use it to find the work done during
adiabatic expansion. Write two limitations of first law of thermodynamics.
7. What do you meant by thermodynamics reversible process? Write two characteristics of a
reversible process.
8. State second law of thermodynamics. One kg mole of a gas at 400 K expand isothermally until
its volume is doubled. Find the amount of work done and heat produced. Given R = 8.3 x 10 -3 J
kgmol-1 K-1.
9. Explain briefly the working principle of a refrigerator and obtain expression for its coefficient of
performance.
10. State and explain Carnot’s reversible with the help of a P-V diagram. Explain the various parts
and steps taken during its cycle of operation. Find expression for the efficiency of a Carnot’s
Engine. What is its advantage.
11. In a Carnot engine, the temperature of the source and sink are 500K and 375K respectively. If
the engine consumes 600 x 103 cal/cycle, find (i) the efficiency of engine (ii) work done/cycle (iii)
heat rejected per cycle.
12. A quantity of air at normal temperature is compressed (i) slowly (ii) suddenly to one third of its
volume. Find the rise in temperature, if any in each case, given ϒ = 1.4.