When a container of water is placed on a laboratory scale,the scale reads 120 g.Now a 20-g piece of copper (of density 8.9 g/cm³)is suspended from a thread and lowered into the water,not touching the bottom of the container.What will the scale now read? The density of water is 1.0 g/cm³. A)120 g B)122 g C)138 g D)140 g

Question

Quizplus · Accepted Answer

When the copper piece is submerged in water, it displaces a volume of water equal to its own weight divided by the density of water. Since the copper does not touch the bottom, the apparent weight increase on the scale is due to the water displaced by the copper. The weight of the displaced water is equal to the weight of the copper (20 g), so the scale now reads 120 g + 20 g = 140 g. However, the question seems to have a discrepancy in the provided choices, as the explanation points towards an answer not listed (140 g). Given the choices, the closest correct interpretation based on the principle of buoyancy and the provided options would be to consider the scale reading as 140 g, but since this option is not available, and considering the possible misunderstanding in the explanation, the correct choice based on the displacement principle and the options given should be reconsidered.

When a Container of Water Is Placed on a Laboratory