PYQ Bank

n identical drops of water, each of radius r_{2}, coalesce to form a large drop of radius R. Calculate the energy released in the process and the consequent rise in temperature of water.

A neutron having kinetic energy E collides head on with a _{6}^{12}\text{C} nucleus and rebounds perfectly elastically in the direction from which it came. Determine the kinetic energy of the neutron after collision.

Calculate the mass of the Sun, given the distance of the Earth from the sun to be 1.5 \times 10^{8}\text{ km}.

Calculate the velocity of an electron having kinetic energy 1 MeV.

The earth receives from the Sun 1.37\times 10^{3}\text{ W/m}^{2} of power on the top of the atmosphere. Calculate the mass of the Sun that is converted into energy in one second.

A rocket is fired vertically up. During the burning of the engine, which lasts for 50\text{ s}, a constant acceleration of 2.0\text{ g} is observed. What is the speed of the rocket at the end of 50\text{ s}? Calculate the maximum height to which the rocket will rise before it begins to fall back. Take = g = 9.80\text{ ms}^{-2} and neglect the variation of g with height.

Water is observed to flow through a capillary of diameter 1.0\text{ mm} with a speed of 3\text{ ms}^{-1} viscosity of water in c.g.s. units is : 0.018 at 0^{\circ}\text{C} 0.008 at 30^{\circ}\text{C} 0.004 at 70^{\circ}\text{C} Calculate he Reynolds numbers, and test at which of these three temperatures is the flow likely to be streamlined.

Explain clearly why Young's modules Y of a material determines the resistance to bending of a thin rod made of that material. Derive the expression for the work done when a wire of length l and cross-sectional area A is stretched by an amount x(\le l) under a given load corresponding to equilibrium at stretching x.

Write a note on Bernoulli's theorem and its applications.