Gravitation Worksheet-11

Gravitation Worksheet-11

71. What is the other name of buoyant force?

72. Name the force which makes heavy objects appear light when immersed in a liquid.

73. What is upthrust?

74. Name the principle which gives the magnitude of buoyant force acting on an object immersed in a liquid.

75. The relative density of mercury is 13.6. what does this statement mean?

76. What name is given to ‘thrust per unit area’ ?

77. What is the scientific name of the ‘upward force’ acting on an object immersed in a liquid?

78. What is meant by the term ‘buoyancy’?

79. What causes buoyant force (or upthrust) on a boat?

80. Why does ice float in water?

81. What force acting on an area of 0.5 m² will produce a pressure of 500 Pa?

82. An object of weight 200 N is floating in a liquid. What is the magnitude of buoyant force acting on it?

83. Name the scientist who gave the magnitude of buoyant force acting on a solid object immersed in a liquid.

84. The density of gold is 19 g/cm³. Find the volume of 95 g of gold.

85. What is the mass of 5 m³ of cement of density 3000 kg/m³?

86. What is the density of a substance of mass 100 g and volume 10 cm³?

87. Why does a block of wood held under water rise to the surface when released?

88. The density of a body is 800 kg/m³. Will it sink or float when dipped in a bucket of water? (Density of water = 1000 kg/ m³).

89. (a) What is the difference between the density and relative density of a substance ?

(b)  If the relative density of a substance is 7.1, what will be its density in SI units ?

90. Define thrust. What is its unit ?

Answer:

71. Upthrust

72. Buoyant force

73. –

74. Archimedes’ principle

75. The relative density of a substance expresses the heaviness of the substance in comparison of water.

76. Pressure

77. Buoyant force (or Upthrust)

78. The object appears to be less heavy in water because the water exerts an upward force on them. The tendency of a liquid to exert an upward force on an object placed in it, is called buoyancy.

79. –

80. –

81. Using pressure P = force/area

250 N

82. 200 N

83. Archimedes

84. Using density D = mass/volume

5 cm³

85. Using density D = mass/volume

15000 kg

86. Using density D = mass/volume

10 g/cm³

87. –

88. Float in water

89. A substance is defined as mass of the substance per unit volume.

The relative density of a substance is the ratio of its density to that of water. That is:

Relative density of as substance

(b) 7.1 × 10³ kg/m³

90. The force acting on a body perpendicular to its surface is called thrust.

Thrust per unit area is called pressure. That is:

The SI unit of thrust is Newton (N).