More difficult question in Science(Please help me!) (15)

Question

8.Why mustn't objects of the same volume volume have the same mass?

(a) Why do some matters float, but some sink in fluid?

(Write down your answer to question 8(a) and please answer the question completely and clearly.)

Thanks a lot for answer my question.

Answer 1

There is a quantity called density. It is defined by density = mass / volume.

Different objects can have different densities. So, objects of the same volume can have different mass.

Water has a density of 1 g per cubic centimetre. If a matter has a density greater than that of water, say, 1.2 g per cubic centimetre, this matter will sink in water. If a matter has a density lower than that of water, say, 0.8 g per cubic centimetre, this matter will float on water.

Answer 2

8.Why mustn't objects of the same volume volume have the same mass?

From the analyses of the students’ responses to the test items 2, 7, 15 and 20, it is clear that most of the students had the misconception that weight or mass determines whether an object sinks or floats. The percentages of the students who had this misconception were in the range of 40-66% for different items (see Table 2). It is possible to conclude that students probably construct some non-scientific rules guided by their limited daily life experiences. This misconception may stem from both students’ lack of knowledge and their inaccurate generalization.

(a) Why do some matters float, but some sink in fluid?

As a serious athlete, Chris says he floats "to decrease the recovery time
from the abuses of weight training. I go in stiff, and come out with a very
positive physical response." These toxins, which cause tension and soreness
apparently leave the muscles much more quickly after a float than they
normally would.

but some sink in fluid because the height effect on bubble dynamics in a microchannel is experimentally studied. We reported that the critical size for a nucleation site to be active increases linearly with the channel height. However, once a bubble is formed, its evolution from incipience to departure can also be channel-size dependent. Thus, various microchannel heat sinks have been fabricated, about 5-10µm in height, with integrated temperature sensors utilizing Si-to-glass anodic bonding technology. Nucleation sites have been formed on the microchannels bottom silicon surface in order to ensure regular bubble formation, while the sensors allow continuous monitoring of the wall temperature. The microchannels are capped by a glass wafer; hence, it is possible to record the bubble activity using video equipment. The three aspects of bubble dynamics: growth rate, departure size and release frequency have been characterized experimentally, and proper control parameters have been identified.