LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034
B.Sc. DEGREE EXAMINATION – PHYSICS
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SECOND SEMESTER – APRIL 2008
PH 2501 – MECHANICS
Date : 23/04/2008 Dept. No. Max. : 100 Marks
Time : 1:00 – 4:00
SECTION – A
Answer all the questions. 10×2 = 20 Marks
- State the law of conservation of angular momentum.
- Find the center of mass of three particles of 1kg, 2kg, and 3kg placed at the three corners of an
equilateral triangle of 1metre side.
- What are the conditions of equilibrium of a rigid body acted on by three coplanar forces?
- Define: (i) Metacentre and (ii) Metacentric height.
- What is meant by effusion of gases?
- State Torricelle’s theorem.
- What are generalized coordinates? What is the advantage of using them?
- State the principle of virtual work.
- What is a frame of reference? Distinguish between inertial and non-inertial frames.
10.Explain the law of addition of relativistic velocities.
SECTION B
Answer any four questions. 4×7.5 = 30 Marks
- What is a torsional pendulum? Derive an expression for the time period of oscillation of a
torsional pendulum.
12 (a) Define center of gravity.
(b) Determine the position of centre of gravity of a solid tetrahedron.
- (a) State and explain Graham’s law of diffusion of gases.
(b) Obtain the equation of continuity for an incompressible fluid in streamline flow.
- Apply Lagrange’s equation to determine
(a) motion of a single particle in space and
(b) time period of oscillation of a simple pendulum.
- (a) Explain time – dilation with an example.
(b) A π meson has a mean lifetime of 2×10-8s when measured at rest. How far does it go before
decaying into another particle if its speed is 0.99c?
SECTION C
Answer any four questions. 4×12.5 = 50 Marks
- What is a compound pendulum? Derive an expression for its time period of oscillation. Explain how the value of g is determined using it.
- (a) Define centre of pressure. Determine the position of center of pressure of a rectangular lamina immersed vertically in a liquid with one edge in the surface of the liquid.
(b) Find the thrust on the rectangular end of a tank of width 0.8m and depth 0.5m filled
completely with water. Find the position where it acts.
- State and prove Bernoulli’s theorem. Discuss any two applications of this theorem.
- (a) State an explain D’Alembert’s principle.
(b) Derive Lagrange’s equations of motion from D’Alembert’s principle for a holonomic
conservative system.
- (a) State the basic postulates of Einstein’s special theory of relativity. Derive the Lorentz space –time transformation formulae.
(b) A rod 5 metre long is moving along its length with a velocity 0.8c. Calculate its length as it appears to an observer on the earth.