CBSE Guess > Papers > Important Questions > Class XI > 2007 > Physics > Physisc By : Mr. Satya Bhushan Sharma

CBSE CLASS XI

Q. 1. Express 5893 A in nm.

Q. 2. When will the relative velocity of two moving objects be zero?

Q. 3. A ball is thrown straight up. What is its velocity and acceleration at the top?

Q. 4. Define efficiency of heat engine.

Q. 5. Define angle of repose.

{2 marks each}

Q. 6. Convert 1 J into erg.

Or

1N into dyne.

Q. 7. A body travels A to B at 40 m/s and B to A at 60m/s. Calculate the average speed and average velocity.

Q. 8. If the distance travelled by a body in time t is given by x=a t + b t2 then what will be the instantaneous acceleration of the body?

Q. 9. Prove that when the angle between two vectors of equal magnitude is 2π/3, the magnitude of their resultant is equal to either of them.

Q. 10. A man can jump on moon six times as high as on earth. Why?

Q. 11. Calculate angular speed of (1) hour hand of a watch and (2) earth about its own axis.

Q. 12. Calculate the impulse necessary to stop a 1500kg of car traveling at 90 km/hr.

{3 marks each}

Q. 13. State and prove work energy theorem.

Q. 14. The radius of earth’s orbit is 1.5 X 10 11m and its period of radiation is 3.2 X 107s.What will be (a) magnitude of the velocity and (b) the centripetal accel. of the earth in its motion around the Sun.

Q. 15. Define moment of inertia. The MI of a circular ring about an axis passing through its centre and perpendicular to its plane which is 200g cm2. If radius of the ring is 5 cm, find its mass.

Q. 16. Define vector. Prove that vectors a= i+2 j+3 k and b=2 i- j are perpendicular to each other.

Q. 17. State and explain angle of contact. Draw figures.

Q. 18. Find Poiseuillis formula.

Or

Find an expression for terminal velocity.

Q. 19. State the relationship between C, F and R scale. Find the temperature for which the reading on Celsius and Fahrenheit scale is same.

Q. 20. Define specific heats of a gas. Cp is greater than Cv. Why?

Q. 21. State: - (a) First law of thermodynamic. (b) Second law of thermodynamic. (c) Newton’s law of cooling.

Q. 22. A SHM is represented by y (t) =10 Sin (20 t + 0.5) m .Find amplitude, frequency and initial phase.

Q. 23. State &explain Doppler’s effect in sound (Any two cases)

Q. 24. Explain the formation of stationary waves in case of a pipe open at both ends diagrammatically.

{5 marks each}

Q. 25. Discuss banking of tracks. Find maximum permissible speed for a vehicle on a banked road.

Q. 26. What is escape velocity? Obtain the expression for the escape velocity on earth? Find escape velocity sson the surface of the earth.

Or

Define orbital velocity. An artificial satellite is going around the earth close to its surface. Calculate the orbital velocity and time taken by it to complete one round. Given Re=6400 Km & g=9.8 m/s².

Q. 27. State and prove Bernoulli’s theorem.