Saturday, October 2, 2010

THRUST AND PRESSURE, BUOYANCY, DENSITY ….

  THRUST AND PRESSURE

1.      Why can a camel run in a desert easily?
2.      Why does an army truck rest upon a continuous chain?
3.      Why do trucks and motorbuses have wider tyres?
4.      Why do cutting tools have sharper edges?
5.      Why does a nail have a pointed tip?
6.      Why do buildings have wide foundation?
7.      It is difficult to hold a school bag with a thin strap or a string. Why?
8.      What is thrust?
9.      What is pressure?
10.  Explain the principles of thrust and pressure by giving suitable examples.
11.  The effects of forces of the same magnitude on different areas are -------------------- .
12.  The effect of thrust depends on the ------------------- .
13.  The effect of thrust on sand is ---------------- while standing than while ----------------- .
14.  The thrust on unit area is called ------------------ .
15.  Complete the following:
Pressure = ---------------
16.  SI unit of pressure is ------------- or -------------------.
17.  SI unit of pressure is called Pascal denoted as --------------, in honour of scientist --------------- .
18.  The same force acting on a smaller area exerts -------------------------.
19.  The same force acting on a larger area exerts -------------------------.

PRESSURE IN FLUIDS
20.  Fluids have weight and they exert pressure on the ------------ and wall of the container.
21.  Pressure exerted in any confined mass of fluid is --------------- ---------------------- in all directions.

BUOYANCY
22.  Why do you feel lighter in a swimming pool?
23.  While drawing water from a well the bucket is lighter when it is inside the water level and heavier when it is out..why?
24.  A ship made of iron and steel does not sink in water, whereas a sheet made of the same metals sink in water. Why?
25.  Define buoyancy.
26.  Explain buoyancy by doing an activity.
27.  Weight of an object is the ----------------- due to gravitational attraction of the earth.
28.  All objects experience ------------------------- when they are immersed in a fluid.
29.  The upward force exerted by the water on a given object is known as ---------------------- or -----------------------------.
30.  The magnitude of the buoyant force depends on the density of the fluid. True or False?

WHY OBJECTS FLOAT OR SINK WHEN PLACED ON THE SURFACE OF WATER?

31.  Why do objects float or sink when placed on the surface of water? Explain with an activity.
32. When would an object float in a liquid?
33. When would an object sink in a liquid?

ARCHIMEDES' PRINCIPLE

32. Define Archimedes' Principle.
33. Explain Archimedes' Principle with an example.
34. List the applications of Archimedes' Principle.

RELATIVE DENSITY

35. What is density?
36. What is the unit of density?
37. Define relative density.
38. Relative density = ---------------------.
39. Relative density has an unit. True or False?

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