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Question :
41. Legend says that Archimedes, in determining whether or not : 2102175

41. Legend says that Archimedes, in determining whether or not the king's crown was made of pure gold, measured its volume by the water displacement method. If the density of gold is 19.3 g/cm^{3}, and the crown's mass is 600 g, what volume would be necessary to prove that it is pure gold?

A. 31.1 cm^{3}

B. 114 ´ 10^{3} cm^{3}

C. 22.8 ´ 10^{3} cm^{3}

D. 1.81 ´ 10^{-2 }cm^{3}

42. A solid rock, suspended in air by a spring scale, has a measured mass of 9.00 kg. When the rock is submerged in water, the scale reads 3.30 kg. What is the density of the rock? (water density = 1 000 kg/m^{3})

A. 4.55 ´ 10^{3} kg/m^{3}

B. 3.50 ´ 10^{3} kg/m^{3}

C. 1.20 ´ 10^{3} kg/m^{3}

D. 1.58 ´ 10^{3} kg/m^{3}

43. As ice floats in water, about 10% of the ice floats above the surface of the water. If we float some ice in a glass of water, what will happen to the water level as the ice melts?

A. The water level will rise 10% of the volume of the ice that melts.

B. The water level will rise, but not as much as the 10% indicated in answer a.

C. The water level will remain unchanged.

D. The water level will become lower.

44. A large stone is resting on the bottom of the swimming pool. The normal force of the bottom of the pool on the stone is equal to the:

A. weight of the stone.

B. weight of the water displaced.

C. sum of the weight of the stone and the weight of the displaced water.

D. difference between the weight of the stone and the weight of the displaced water.

45. A blimp is filled with 400 m^{3} of helium. How big a payload can the balloon lift? (The density of air is 1.29 kg/m^{3}; the density of helium is 0.18 kg/m^{3}.)

A. 111 kg

B. 129 kg

C. 215 kg

D. 444 kg