Friday, August 17, 2012

CBSE Class 9 - Science - CH10 - Gravitation (Worksheet-1)

Nicolaus Copernicus - His theory
was one the trigger point for
scientific revolution.
Fill in the Blanks

1. Geocentric model i.e. the Earth is the orbital centre of all celestial bodies was proposed by _____.

2. Heliocentric model was proposed by ______.

3. According to the Heliocentric theory, the _____ is at centre and _______ move around it.

4. ______ stated that every planet moves around the sun in closed elliptical orbit, with the ___ at one focus.

5. The force which keeps the object moving in a circular path is called _____ force. It always acts towards the _____.

6. The force of attraction between two objects is ______ proportional to the product of their masses and _____ proportional to the square of a distance between them.

7. Kepler's Law of ______ states that a line that connects a planet to the Sun sweeps out equal ______ in the plane of the planet's orbit in _____time intervals.

8. The value of Universal Gravitation constant (G) is ________ Nm2kgs-2.

9. The mass of the earth is ________ kg.

10. The mass of an object  _____ (varies/does not vary) on the earth as well as on the moon. But its weight  is ______(same/different) on both places.

11. When objects of different masses and sizes are dropped from same height would reach the ground at ______ (same time/different times), considering negligible air resistance.

12. Acceleration due to gravity (g) is _______ (dependent/independent) of mass.

13. The value of g on the earth's surface is ______.

14. The value of g at poles is ______ (lower/higher) than its value at the equator.

15. The value of g ________ (increases/decreases) as we go upwards from the earth's surface.

16. The value of g ________ (increases/decreases) as we go downwards from the earth's surface.

17. The SI unit of weight is _____.

18. Weight of an object is the product of  ______ and ________.

19. At the centre of the earth, the acceleration due to gravity is _______.

20. The value of G was found out by _______ by using a ________.

Gravitation Important Formulae

1. Ptolemy
2. Copernicus
3. sun, planets
4. Kepler's Law of Orbits, Sun
5. Centripetal, centre
6. directly, inversely
7. Law of Areas, areas, equal
8. 6.67 × 10-11
9. 6. x 1024 kg

10. does not vary, different
11. same time
12. independent
13. 9.8 m/s2
14. higher
15. decreases
16. decreases
17. Newton (N)
18. mass of the object(m), acceleration due to gravity(g)
19. zero.
20. Henry Cavendish, sensitive balance

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