17 March 2012

CBSE Practice Papers Class IX Gravitation

CBSE SA-II Physics Chapter-Gravitation (Newton’s laws  for Gravitation)
1. Sate Newton's law of motion. Derive it.
2. Define
a) Gravity and an expression for acceleration due to gravity
b) Pressure
c) Free fall
3. If the earth attracts an apple does the apple also attract the earth? If yes, why does the earth not move towards the apple?
4. Why does a mug full of water feel lighter inside water?
5. A perpendicular force of 50N acting on a surface generate a pressur of 250pa. Calculate area of cross section of surface on which pressure is acting.
6. Why and when does acceleration due t gravity acting on a body change.
7. A body has 40kg mass. Calculate it's wt. when it is taken to a planet whose mass is 4 times the earth and radius half then that of the earth.
8. How does the wt. of a body gets affected when the is taken to poles from equator?
9. Wy does the moon not actujally fall on the surface of the earth?
10. State the difference between mass and weight.
11. A bar of gold has mass of 100g ad weight is9.8 N at some place when it is taken to some place at equator mass remains 100g but wt. is <0.98. Explain.
12. If the force of gravity vnishes why would we be flying in space?
13. A bag of sugar weighs W at a certain pace at equator. If this bag is taken to Antertica will th wt. remain the same or more or less? Why
14. Give reasons:
a) Sleepers are provided under railwayn tracks
b) It is difficult to dross a rsert on a horce back.
c) The bull of a rifle is very broad but tip of bullet is pointed.
d) Dams are made wide at base
e) Cuttin instruments are often sharpened
f) Board pins are broad at the end and ointed on the other.
g) Skier's sink in fresh snow.
h) Sledges used by eskimos have no wheels.
15. Calaulate the pressure when force of 1000N acts on 2m2 area.
16. Calculate the force if it produces a pressure of 50000pa. over 0.125m2.
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