Gravitation-Class -IX- Vasu Classes

1. When two forces are applied on the same object in the same direction the resultant force is

a) Equal to difference of the forces
b) Equal to sum of the forces
c) Zero
d) None

2. The SI unit of pressure is

a) N/m2
b) dyne/cm2
c) Pascal
d) Kg/m2
e) A and C

3. Heavy tanks have broad chains called caterpillar tracks

a) to decrease contact area
b) to increase contact area and decrease pressure
c) to derease contact area and decrease pressure
d) All of the above

4. A block of wood is floating in a lake. The apparant weight of the block is ....

a) same as that in air
b) less than that in air
c) more that in the air
d) Zero

5. Upthrust acting on an immersed body depends upon

a) density of the fluid
b) density of body
c) volume of body
d) Both density of fluid and volume immersed of the object

6. A force of 50N is applied to an object of area 2 sqm. Then the pressure on the object is.....N/sqm

a) 15
b) 25
c) 35
d) 100

7. A hydrometer sinks deeper in a liquid of...... density than in a liquid of........density.

a) lower, higher
b) higher, lower
c) lower, lower
d) higher, higher

8. It is easier to swim in sea water than in river water

a) true
b) false

9. Two bodies have equal volumes and their masses are in the ratio of 1:4. The ratio of their densities will be..

a) 1;4
b) 4:1
c) 2:1
d) 3:1

10. The mass of the log of a wood is 120kg. It is floating in water. what weight must be placed on it to make it just sink?

a) 100kg
b) 70kg
c) 120kg
d) 80kg

11. An object just floats in water. If common salt is added into water

a) immersed volume increases
b) decreases
c) remains same
d) the object first sinks then floats up

12. A substance floats in water but sinks in cocomut oil. The density of the substance is

a) less than the density of water
b) more than the density of the oil
c) more than the density of water
d) None

13. The weight of a bodty in air is 50gm. Its volume is 10 cubic cm. What will be its weight in water?

a) 40gm
b) 50gm
c) 60gm
d) 30gm

14. Weight of a metal piece in air is 120gm in air , 100 gm in water and 110gm in a liquid. Then RD of metal is

a) 6
b) 12
c) 4
d) 3

15. Name the device used to measure the purity of milk

a) lactometer
b) barometer
c) manometer
d) hydrometer

16. A block of wood floats in a liquid of density 0.8gm/cubic cm with 1/4 th of its volume submerged. In a oil the block floats with 60% of its volume submerged. What will be the density of oil?

a) 666.6gm/cc
b) 333.3gm/cc
c) 444.5gm/cc
d) None

17. Weight of a solid in air is 50N and in water when completely immersed 40N. What will be its R.D

a) 6
b) 5
c) 4
d) 3

18. The volume of 50gm of a substance is 20 cm3. If the density of water is 1gm/cm3, the object will float

a) True
b) False

19.

First calculate immersed volume of wooden piece.

A piece of wood having volume 72cm3 and density 0.84gm/cm3 floats in a brine of density 1.2gm/cm3. What volume of brine is displaced?

a) 66.5cm3
b) 45cm3
c) 50.4cm3
d) 78cm3

20. Mass of a planet is twice the mass of the Earth and radius is thrice of the earth what will be the value of g on the planet

a) Twice of that on the Earth
b) 4.5 times
c) 2/9 of that on the Earth
d) None

21. The distance between two bodies has been increased by 10% , by what percent force of gravitation between the bodies changes

a) 25%
b) 40%
c) 15.75%
d) 23.46%

22. If the diameter of the Earth becomes twice of the present value and the mass remains the same , how would the weight of a body affected

a) 2W
b) 1/2W
c) 3W
d) 1/4W

23. A stone is dropped from the roof of a house it reaches the ground in one second , what is the height of the house?

a) 9.8m
b) 4.9m
c) 12m
d) 19.6m

24. If a man weighs 60kg on the surface of the earth , at what height his weight would be 30kg

a) R/2
b) 0.41R
c) R/4
d) R/3

25. The value of g is maximum

a) at poles of the earth
b) at equator of the earth
c) in a mine
d) at the centre of the earth

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