HSC Physics 1st Paper Model Test-1

Class – XII

Subject: Physics 1st Paper

Time : 3 hrs.                                                                                                                                         Marks.75

1.	(a)  Prove the equation, S = vot + a t2 at by calculus.	5
	(b)  Derive an expression for work done by variable force.	5
	(c)  What is centripetal force? The radius of curvature of a circular path is 100m. What will be the angle of inclination of the path for a speed of 60 kmh-1?	1+4=5
Or,	(a)  Describe Cavendish method for the determination of gravitational constant G.	6
	(b)  Prove that the motion of a simple pendulum at small amplitude is simple harmonic motion.	5
	(c)  Calculate the terminal velocity of a rain drop of diameter 0.0 3mm. The coefficient of viscosity of air is 1.8 10-5 Nsm-2 and its density is 1.2 kgm-3.	4
2.	(a)  Show that presure of a gas in two third of the K.E of molecules per unit votume.	6
	(b)  Show that for an ideal gas in adiabatic process  = constant.	5
	(c)  Explain green house effect form wein's law.	4
Or,	(a)  Discuss a method for determining latent heat of fusion of ice.	5
	(b)  Show that entropy of a system remains constant in reversible process.	5
	(c)  What is entropy? The efficiency of a car not's enjine is 40% and the temperature of the source.	2+3=5
3.	(a)  Explain the interference of sound. Establish the conditions for constructive and destructive interference.	5
	(b)  Show that vibrations of air column pipe closed at one end produce odd harmonics of fundamental tone.	5
	(c)  Define phase. The speed of sound in media P and Q are 300 ms-1 and 350 ms-1 respectively. If the difference of wavelength of a wave in those media is 0.1 m. Find the distance travelled in medium for 50 vibrations.	1+4=5
Or,	(a)  Describe the method of resonant air column for the determination of velocity of sound including end correction.	6
	(b)  Derive an expression for the apparent frequency of sound when the source is moving away from the observer.	5
	(c)  Two tuning forks produce wavelengths of 0.80m and 0.804 m in air. If 2 beats one formed, then find the speed of sound in air.
4.	Define position vector. If   =     and are parallel to each other, determine the value of m.	5
Or,	Derive E  and define unit force.
5.	What is escape velocity? Derive its equation	5
Or,	Determine the deferential equation of a simple harmonic motion and show that x = A sin ( wt +) is its solution.
6.	Show that elastic potential energy per unit volume of body = stress  strain .
Or,	Define angle of friction 10N force acts on a body at rest of mass 2kg. If after 4 sec, the force does not act on the body. Find the distance travelled in 8 see from begining.
7.	What is called mean free path? What the kinetic energy per mole of Helium at 270c
Or,	Define thermometric property. A faulty thermometer reads the melting point of ice 10c and boiling point of water 980c. When this thermometer reads 400c. What is the actual termperature?
8.	What is the importance of g ? A block body is kept at 3270c . Find the wavelength corresponding to the maximum radiant energy.	5
Or,	State and explain second law of thermodynamics. What do you understand by thermal death of the universe?
9.	What is intensity of sound? Derive the equation V = fl.	5
Or,	Define decibel. Derive the equation of intensity level.