Comprehension
Answer these questions based on the passages.
For years, the contents of a child's sandbox have confounded some of the nation' s top physicists. Sand and other granular materials, such as powders, seeds, nuts, soils, and detergent, behave in ways that seem to undermine natural laws and cost industries ranging from pharmaceuticals to agribusiness and mining, billions of dollars.
Just shaking a can of mixed nuts can show you how problematic granular material can be. The nuts do not 'mix' ; they 'unmix' and sort themselves out, with the larger Brazil nuts on top and the smaller peanuts at the bottom. In this activity and others, granular matter' s behaviour apparently goes counter to the second law of thermodynamics, which states that entropy, or disorder, tends to increase in any natural system.
Mimicking the mixed-nut conundrum with a jar containing many small beads and one large bead, one group of physicists claimed that vibrations causing the beads to percolate open up small gaps rather than larger ones. Thus, when a Brazil nut becomes slightly airborne, the peanuts rush in underneath and gradually nudge it to the top. Another group of physicists colour coded layers of beads to track their circulation in a container and achieved a different result. Vibrations, they found, drive the beads in circles up the centre and down the sides of the container. Yet downward currents, similar to convection currents in air or water, are too narrow to accommodate the larger bead, stranding it on top.
One industrial engineer who has studied the problem says that both the 'percolation' and 'convection current' theories can be right, depending upon the material, and that percolation is the major factor with nuts. Given the inability of scientists to come up with a single equation explaining unmixing, you can see why industrial engineers who must manage granular materials go a little, well, 'nuts'! Take Pharmaceuticals, for instance. There may be six types of powders with differentsized grains in a single medicine tablet. Mixing them at some speeds might sort them, while mixing at other speeds will make them thoroughly amalgamated. One aspirin company still relies on an experienced employee wearing a latex glove who pinches some powder in the giant mixing drum to see if it 'feels right'.
Granular material at rest can be equally frustrating to physicists and engineers. Take a tall cylinder of sand. Unlike a liquid, in which pressure exerted at the bottom increases in direct proportion to the liquid' s height, pressure at the base of the sand cylinder doesn' t increase indefinitely. Instead, it reaches a maximum value and stays there. This "quality allows sand to trickle at a nearly constant rate through the narrow opening separating the two glass bulbs of an hourglass, thus measuring the passage of time
Physicists have also found that forces are not distributed evenly throughout granular material. It is this characteristic that may account for the frequent rupturing of silos in which grain is stored. In a silo, for instance, the column's weight is carried from grain to grain along jagged chains. As a result the container' s walls carry more of the weight than its base, and the force is significantly larger at some points of contact than at others. Coming up with equations to explain, much loss, predict the distribution of these force chains" is extremely difficult.
Again, using beads, physicists developed a simple theoretical model in which they assume that a given bead transmits the load it bears unequally and randomly onto the three beads on which it rests. While the model agrees well with experimental results, it does not take into account all of the mechanisms of force transmission between grains of sand or wheat.
In the struggle to understand granular materials, sand-studying physicists have at least one thing in their favour. Unlike particle physicists who must secure billions of dollars in government funding for the building of super-colliders in which to accelerate and view infinitesimal particles, they can conduct experiments using such low-cost, low-tech materials as sand, beads, marbles, and seeds. It is hoped that more low-tech experiments and computer simulations will lead to equations that explain the unwieldy stuff and reduce some of the wastage, guesswork, and accidents that occur in the various industries that handle it.
For years, the contents of a child's sandbox have confounded some of the nation' s top physicists. Sand and other granular materials, such as powders, seeds, nuts, soils, and detergent, behave in ways that seem to undermine natural laws and cost industries ranging from pharmaceuticals to agribusiness and mining, billions of dollars.
Just shaking a can of mixed nuts can show you how problematic granular material can be. The nuts do not 'mix' ; they 'unmix' and sort themselves out, with the larger Brazil nuts on top and the smaller peanuts at the bottom. In this activity and others, granular matter' s behaviour apparently goes counter to the second law of thermodynamics, which states that entropy, or disorder, tends to increase in any natural system.
Mimicking the mixed-nut conundrum with a jar containing many small beads and one large bead, one group of physicists claimed that vibrations causing the beads to percolate open up small gaps rather than larger ones. Thus, when a Brazil nut becomes slightly airborne, the peanuts rush in underneath and gradually nudge it to the top. Another group of physicists colour coded layers of beads to track their circulation in a container and achieved a different result. Vibrations, they found, drive the beads in circles up the centre and down the sides of the container. Yet downward currents, similar to convection currents in air or water, are too narrow to accommodate the larger bead, stranding it on top.
One industrial engineer who has studied the problem says that both the 'percolation' and 'convection current' theories can be right, depending upon the material, and that percolation is the major factor with nuts. Given the inability of scientists to come up with a single equation explaining unmixing, you can see why industrial engineers who must manage granular materials go a little, well, 'nuts'! Take Pharmaceuticals, for instance. There may be six types of powders with differentsized grains in a single medicine tablet. Mixing them at some speeds might sort them, while mixing at other speeds will make them thoroughly amalgamated. One aspirin company still relies on an experienced employee wearing a latex glove who pinches some powder in the giant mixing drum to see if it 'feels right'.
Granular material at rest can be equally frustrating to physicists and engineers. Take a tall cylinder of sand. Unlike a liquid, in which pressure exerted at the bottom increases in direct proportion to the liquid' s height, pressure at the base of the sand cylinder doesn' t increase indefinitely. Instead, it reaches a maximum value and stays there. This "quality allows sand to trickle at a nearly constant rate through the narrow opening separating the two glass bulbs of an hourglass, thus measuring the passage of time
Physicists have also found that forces are not distributed evenly throughout granular material. It is this characteristic that may account for the frequent rupturing of silos in which grain is stored. In a silo, for instance, the column's weight is carried from grain to grain along jagged chains. As a result the container' s walls carry more of the weight than its base, and the force is significantly larger at some points of contact than at others. Coming up with equations to explain, much loss, predict the distribution of these force chains" is extremely difficult.
Again, using beads, physicists developed a simple theoretical model in which they assume that a given bead transmits the load it bears unequally and randomly onto the three beads on which it rests. While the model agrees well with experimental results, it does not take into account all of the mechanisms of force transmission between grains of sand or wheat.
In the struggle to understand granular materials, sand-studying physicists have at least one thing in their favour. Unlike particle physicists who must secure billions of dollars in government funding for the building of super-colliders in which to accelerate and view infinitesimal particles, they can conduct experiments using such low-cost, low-tech materials as sand, beads, marbles, and seeds. It is hoped that more low-tech experiments and computer simulations will lead to equations that explain the unwieldy stuff and reduce some of the wastage, guesswork, and accidents that occur in the various industries that handle it.
Question: 1
The percolation theory of unmixing is bout illustrated by which of the following examples?
The percolation theory of unmixing is bout illustrated by which of the following examples?
Updated On: Oct 7, 2024
- Contents settling in a bag of potato chips so that the package appears less full after handling.
- Currents of small beads blocking the upward movement of large beads in a shaken container.
- Larger rocks rising to the surface in a garden after a period of frost.
- Largo nuts blocking the upward movement of small nuts in a shaken container.
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The Correct Option is D
Solution and Explanation
The correct option is (D): Largo nuts blocking the upward movement of small nuts in a shaken container.
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Question: 2
In saying that the percolation and convection current theories may both be right, the industrial engineer means that.
In saying that the percolation and convection current theories may both be right, the industrial engineer means that.
Updated On: Oct 7, 2024
- though the theories have different names, they describe same physical mechanism.
- both theories are still unproven, as they have not been tested on a variety of materials.
- neither theory is supported by an adequate mathematical basis.
- the mechanism causing unmixing varies depending upon the type of granular material.
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The Correct Option is D
Solution and Explanation
The correct option is (D): the mechanism causing unmixing varies depending upon the type of granular material.
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Question: 3
Which of the following appears to be the best solution for combating the 'unmixing' problem faced by pharmaceutical manufacturers that must prepare large quantities of powders?
Which of the following appears to be the best solution for combating the 'unmixing' problem faced by pharmaceutical manufacturers that must prepare large quantities of powders?
Updated On: Oct 7, 2024
- To mix all the powders together at the same speed.
- To craft powders in which every grain weighs the same amount.
- To craft powders so that all the grains have similar sizes and shapes.
- To hire engineers who have years of experience in powder mixing.
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The Correct Option is D
Solution and Explanation
The correct option is (D): To hire engineers who have years of experience in powder mixing.
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Question: 4
The passage implies that if the top bulb of an hourglass were filled with water instead of sand the pressure pushing the water through the opening would
The passage implies that if the top bulb of an hourglass were filled with water instead of sand the pressure pushing the water through the opening would
Updated On: Oct 7, 2024
- remain constant as water trickles through the opening.
- decrease as water trickles through the opening.
- increase as water trickles through the opening.
- be directed at the walls of the container rather than the base.
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The Correct Option is B
Solution and Explanation
The correct option is (B): decrease as water trickles through the opening.
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Top Questions on Reading Comprehension
- Read the excerpt from a Handicrafts Manual: ‘Advanced Knitting Techniques’ and answer the following questions by choosing the most appropriate answer.
THE FAIR ISLE METHOD: Fair Isle knitting is a traditional technique that involves using two or more colours of yarn in a single row to create intricate patterns and designs. This method requires careful tension management to ensure even stitches and prevent puckering. To begin, select your colours and cast on the desired number of stitches. As you knit, alternate between colours every few stitches, carrying the unused yarn along the back of the work. Mastering the Fair Isle technique allows you to create stunning visual effects in garments, accessories, and home textiles.
THE CONTINENTAL STYLE: The Continental knitting style, often referred to as “picking,” involves holding the yarn in the left hand while the right hand manipulates the needles. This method allows for greater speed and efficiency, particularly when working with complex patterns or multiple colours. To practice this style, start by casting on your stitches and using your left hand to tension the yarn. With each stitch, simply “pick” the yarn with your right needle, forming a quick and fluid motion. As you become comfortable with this technique, you may find that your overall knitting speed and comfort improve significantly.
THE SHORT-ROW TECHNIQUE: Short-row knitting is an advanced technique that allows for the creation of shaped garments, such as sleeves and shoulders, without the need for complex shaping. To make a sleeve using this technique, begin by casting on the required number of stitches. Work a portion of the row, then turn your work and return without completing the full row to create the “short rows” that shape the curves of the sleeve. To prevent holes at the turn, wrap the stitch before you turn your work. Repeat this process as needed to achieve the desired shaping and dimension of the sleeve. Once you have shaped the sleeve, you can then sew the side seams to connect the pieces of your garment and finally, complete the edges to ensure a clean finish. This method not only helps shape curves but also adds dimension to your piece, allowing you to enhance fit and style.- AILET BALLB (Hons.) - 2025
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The Story of Coffee
Coffee, a beloved beverage enjoyed by millions around the globe, has a rich and captivating history that spans centuries. The story of coffee begins in the ancient highlands of Ethiopia, where, according to legend, a goat herder named Kaldi discovered the stimulating effects of coffee beans. One day, Kaldi noticed his goats frolicking with unusual energy after eating red berries from a certain tree. Curious, he tried the berries himself and experienced a newfound alertness. This discovery soon spread to monasteries, where monks used it to stay awake during long hours of prayer. From Ethiopia, coffee cultivation and consumption spread to the Arabian Peninsula, particularly in Yemen, where the practice of roasting coffee beans and brewing the drink began to take shape. By the 15th century, coffee had become a popular beverage in the Islamic world, with coffee houses known as ‘qahveh khaneh’ emerging as social hubs for conversation, music, and intellectual exchange. These coffee houses became centers of culture and commerce, influencing the spread of coffee to Turkey and beyond, eventually reaching Europe. In Europe, coffee initially faced resistance from religious authorities who considered it a ‘Muslim drink’ and tried to ban it. However, its popularity persisted, and by the 17th century, coffee houses had sprung up in major European cities, becoming important gathering places for artists, writers, and thinkers. The stimulating effects of coffee were embraced during the Age of Enlightenment, where it was seen as a catalyst for intellectual discussion and innovation. The journey of coffee continued with the establishment of colonial plantations in tropical regions such as the Caribbean, Central and South America, and Southeast Asia. These plantations fuelled the global demand for coffee, transforming it from a regional specialty to a major commodity. The industrial revolution further accelerated coffee production and consumption, leading to innovations in coffee brewing methods and the development of instant coffee. In the modern era, coffee has evolved into a deeply ingrained part of daily life for people worldwide. Its cultural significance spans from the bustling cafes of Paris to the quiet coffee farms of Colombia. Today, coffee remains not only a popular beverage but also a symbol of social interaction, productivity, and enjoyment. Whether sipped slowly over a conversation with friends or grabbed hastily on the way to work, the story of coffee continues to unfold, intertwining with the histories and cultures of countless societies across the globe.- AILET BALLB (Hons.) - 2025
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The intricate world of modern manufacturing is a web of precision and innovation, where even the tiniest components play a pivotal role. One such element, often overlooked but crucial, is the sub-subpart. Whether it’s a carpenter fashioning a bespoke piece of furniture or an automobile engineer designing the next generation of vehicles, the creation of sub-subparts is a fundamental process that demands meticulous craftsmanship and cutting-edge technology. In the realm of woodworking, carpenters frequently work with sub-subparts like dowels, screws, and hinges. These minute components may appear insignificant, yet they determine the structural integrity and functionality of the final product. Crafting a dowel, for instance, begins with selecting the appropriate wood species, followed by precision cutting and shaping. The result is a perfectly cylindrical, sturdy sub-subpart that seamlessly joins two larger pieces of wood. The advent of computer-aided design (CAD) and computer numerical control (CNC) machines has revolutionised this process, enabling carpenters to create sub-subparts with unparalleled precision.
Similarly, in the automobile industry, sub-subparts are the unsung heroes of vehicle construction. Take, for instance, the ball bearing—a minuscule but essential component in the wheels and transmission system. Manufacturing these precision-engineered spheres involves intricate processes like forging, heat treatment, and precision machining. Modern techniques such as laser cutting and 3D printing have streamlined production, ensuring that these sub-subparts meet the demanding standards of the automotive sector. The manufacturing of sub-subparts is a testament to the convergence of traditional craftsmanship and cutting-edge technology. Whether it’s a carpenter’s workshop or a high-tech automotive assembly line, the quest for perfection in sub-subpart creation remains unwavering. The attention to detail and precision required in these processes is a testament to the dedication of craftsmen and engineers alike.
To conclude, while sub-subparts may be small in size, their significance in various industries cannot be overstated. Whether it’s a carpenter working on a timeless piece of furniture or an automotive engineer striving for superior performance, the manufacturing of sub-subparts is a crucial step towards achieving excellence in craftsmanship and technology. This fusion of tradition and innovation accentuates the essence of modern manufacturing.- AILET BALLB (Hons.) - 2025
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