LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034
B.Sc. DEGREE EXAMINATION – PHYSICS
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SECOND SEMESTER – APRIL 2008
PH 2500 – MECHANICS & SOUND
Date : 23/04/2008 Dept. No. Max. : 100 Marks
Time : 1:00 – 4:00
SECTION – A
Answer all the questions. 10×2 = 20 Marks
- Two ships A and B are sailing due east and due south with velocities 30km/hr and 40km/hr respectively. Find the velocity of ship A relative to the ship B.
- What is the physical significance of moment of inertia?
- Define: (i) Metacentre and (ii) Metacentric height.
- Show that the algebraic sum of the moments of two forces forming a couple is equal to the moment of the couple.
- What is meant by phase space?
- Distinguish between holonomic and non-holonomic constraints.
- What are Lissajous’ figures? Mention their uses.
- What are beats? Mention their applications.
- Explain piezo-electric effect.
- What is absorption co-efficient? Mention its unit.
SECTION – B
Answer any four questions. 4×7.5 = 30 Marks
- Obtain an expression for the acceleration of a body rolling down an inclined plane.
- (a) Describe the working of venturimeter.
- The diameter of the throat of a venturimeter is 0.05m. When it is inserted in a horizontal pipe line of diameter 0.1m, the pressure difference between the pipe and the throat equals 0.06m of water. Calculate the rate of flow of water.
- Define the Hamiltonian. Obtain Hamilton’s canonical equations for a holonomic system.
- Describe Melde’s experiment to determine the frequency of a vibrator.
- Explain the production of ultrasonics by magnetostriction method.
SECTION-C
Answer any four questions. 4×12.5 = 50 Marks
- (a) Derive an expression for the moment of inertia of a solid sphere about its diameter.
(b) Find ratio of radius of gyration of a circular disc to that of circular ring of the same radius about the diameter.
- (a) Define centre of pressure.
- Determine the position of centre of pressure for a triangular lamina of height h immersed vertically in a liquid with,
- its vertex and
(ii) its base in the surface of the liquid.
- Derive Lagrange’s equations of motion and apply them to the Atwood’s machine to find the
acceleration of the system.
- (a) Derive an expression for the velocity of longitudinal waves in a gas. Discuss Laplace’s correction.
- The velocity of sound in air at 15˚C is 340m/s. What will it be when the pressure of the gas is doubled and its temperature is raised to 160˚C?
- Define reverberation time. Derive Sabine’s formula for the reverberation time.