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#### Forces and Pressure Book Back Questions

8th Standard EM

Reg.No. :
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Science

Time : 00:45:00 Hrs
Total Marks : 30
3 x 1 = 3
1. If we apply a force against the direction of motion of a body, then the body will

(a)

stop moving

(b)

move with an increased speed

(c)

move with a decreased speed

(d)

move in a different direction

2. Pressure exerted by a liquid is increased by

(a)

the density of the liquid

(b)

the height of the liquid column

(c)

Both (a) & (b)

(d)

None of the above

3. The unit of viscosity is

(a)

N m2

(b)

poise

(c)

kg m s–1

(d)

no unit

4. 3 x 1 = 3
5. The pressure of a liquid column _____ with the depth of the column.

()

Increases

6. The property of _____ of a liquid surface enables the water droplets to move upward in plants.

()

surface tension

7. A simple barometer was first constructed by _____.

()

Torricelli

8. 4 x 1 = 4
9. Force acting on a given area is called pressure.

(a) True
(b) False
10. A body will sink if the weight of the body is greater than the buoyant force.

(a) True
(b) False
11. Friction is the only reason for the loss of energy.

(a) True
(b) False
12. Using barometers, one can measure the height of a building.

(a) True
(b) False
13. 3 x 2 = 6
14. Give two examples to verify that a force tends to change the static condition of a body.

15. Name two instruments, which help to measure the pressure of a fluid.

16. Which has greater viscosity, oil or honey? Why?

17. 3 x 3 = 9
18. How do sailors protect their ship during a heavy storm?

19. Is there any possibility of making a special device to measure the magnitude of friction directly?

20. A bubble rises from the bottom of a pond to its surface by increasing its radius by 3 times its value when it was at the bottom. Calculate the depth of the pond. (Hint: Pressure depends on the depth of the pond. Volume is inversely related to pressure.) [Science Olympiad]

21. 1 x 5 = 5
22. Describe an experiment to prove that friction depends on the nature of a surface.