## Wednesday, March 9, 2011

### Class XI Physics Chapter wise Revision Test - Gravitation and Waves

PHYSICS TESTPAPER

CLASS XI

GRAVITATION AND WAVES

Instructions

Questions 1 to 5 carries one mark each

Questions 5 to 10 carries 2 marks each

Questions 10 to 15 carries 3 marks each

Questions 16 and 17 carries 5 marks each

1. What are mechanical waves?

2. The time period of a vibrating source producing sound is 0.01 s. If the velocity of sound is 340 ms -1 calculate wave length

3. State the principle of superposition of waves

4. Why is gravitational potential energy negative?

5. What is geosynchronous satellite?

6. Derive a relation between wave velocity, frequency and wavelength

7. What are transverse and longitudinal wave motions? Give an example for each type

8. What is the effect of pressure on the speed of sound? Justify your answer.

9. What is a progressive wave? Write an expression which represents a progressive wave.

10. State the conditions necessary for a satellite to appear stationary.

11. Define orbital velocity. Derive an expression for it.

12. Define acceleration due to gravity. Show that the value of ‘g’  decreases with altitude or height

13. State the laws of vibrations of stretched strings.

14. Derive an expression for the escape velocity of a satellite projected from the surface of the earth.

15. What is the maximum value of potential energy that can be possessed by a heavenly body? Give the general expression for potential energy of an object  near the surface of earth

16. State Kepler’s law of planetary motion. Deduce Newton’s law of gravitation from Kepler’s law.

17. (a)What is Doppler Effect?  (b) Derive an expression for the apparent frequency when a source moves towards a stationary observer.  (c) A policeman on duty detects a drop of 15% in the pitch of the horn of a motor car as it crosses him. Calculate the speed of car, if the velocity of sound is 330 m/s

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