Longer passages
The writers are high school seniors, and the occasional graduate student, who are for the most part, native speakers of English. The passages were taken from final revised submissions. They were not made up. Ed.
(a) Read the passages.
(b) Identify the main areas of deficiency in each one.
(c) Rewrite in succinct clear English, in the style of
a research report.
Note: these passages contain deficiencies in style, in the selection of content, in organization, in tense, choice of words, punctuation, etc. They cannot just be edited. A complete rewrite is required. Identify relevant points and rewrite carefully. Aim to reduce the length by more than half.
1 The Photoelectric effect
There are two clean metallic plates in vacuum. When exposed to light the light hits the metallic plate the light energy is converted to photoelectrons which shoot out of the cathode to the anode and cause a current. If a power source were to be placed in opposite direction of the circuit at a certain voltage the flow of photoelectrons to the anode would be repelled and the current would stop. The voltage required to stop the flow is related to the frequency of the light hitting the cathode. At lower frequencies the voltage required to stop the flow of photoelectrons to the anode is higher. This relation is called plank's constant. Plank's constant can be measured in two different ways. One is using the method above; measuring the voltage required to stop current at different frequencies of light and fitting the values to a line. The second uses a p-n junction.
In a p-n junction there are two types of semiconductor materials. One material has extra electrons which is the n material and the other has spaces for extra electrons which is the p material. This causes a barrier voltage drop between the materials. Placing a voltage across this junction will cause current and the diode will light. The point at which the diode is barely lit represents the point of barrier potential. Plotting the voltage required for this at different frequencies will produce a slope equal to Planck's constant
The passage is an attempt to describe the photoelectric effect by a writer who has insufficient command of the language. He has some words in the right places, but many words are used wrongly. The writing is obscure and difficult to decipher, unless the reader knows exactly what is being alluded to. It is impossible to improve the writing - unless the concepts are very clearly understood. Ed.
2 Drag forces in shallow water
There are three basic forces to be considered in fluid dynamics: thrust, which propels the vessel, drag, which resists the propulsion, and lift, which keeps it aloft. In the case of hydrodynamics, lift is primarily supplied by buoyancy but is also created by movement over the water creating an upward force due to the shape of the boat. It is known that making the surface area as small as possible can reduce drag. At low speeds (below Mach .7) the ratio between lift and drag decreases with gains of speed; accordingly, development for many years has stressed increases in thrust over reductions in drag.
The hull of a boat is shaped in a particular way to reduce drag. The drag is the resistance caused by the friction of the water. A conclusion that can be drawn from aerodynamics and applied to hydrodynamics is that shape s obviously a key factor. The shape of a wing or hull affects the amount of friction experienced. However, at some velocity, the thrust equals the drag; this is known as the terminal velocity. At this point acceleration equals zero.
Another variable to be considered is the viscosity of the fluid. This variable will be kept roughly constant by using only tap water.
The passage is an introduction to an investigation. The drag on a model boat was measured as a function of the depth of water below the hull. A pulley and weight system applied a constant known driving force to the boat in a shallow tank. The applied force at terminal velocity was plotted against the depth of water below the hull. Since the driving force equals the drag force at terminal velocity the graph represented the drag force as a function of depth.
The attempted introduction includes a mixture of aerodynamics at high speed, the conditions that provide lift, and the conditions that determine drag. There is no mention of the proximity of the bottom, which influences drag by a mechanism known as the wall effect.
The attempt should be abandoned and a new introduction written that contains relevant background information. Ed.
3 The vibration frequency of a wine glass
The concept of using glass as an instrument has existed for hundreds of years. The Chinese, Persians, Japanese, and Arabs all created music by using sticks to hit glasses filled with water. However, it was not until 1743 that Richard Puckeridge came up with the idea of rubbing the rim of the glasses with a wet finger (Bloch). Inspired by this concept, Benjamin Franklin invented in 1761 the instrument known today as the glass harmonica ("Ben Franklin"). To change the pitch, he manipulated the glass bowl depth and diameter (Bloch). However, since it is difficult to adjust these variables without expensive materials, my goal is to instead find the relationship, if any, between the density of the liquid and the frequency at which the champagne flute filled with that liquid resonates. Because of its availability, I will use sugar to manipulate the density.
Sound is explained by the Macmillan Encyclopedia of Physics as being "carried through waves that propagate through elastic materials and cause alterations in pressure." Giancoli (1998) clarifies this definition, saying that the source of sound is vibration. In this way, the source of sound of a glass harmonica can be explained, because as a finger rubs the rim of the glass it alternately catches and releases, leading to vibrations (Bloch). However, the speed of vibrations varies based on the medium (solid, liquid, gas). This is because a sound wave moves through the collisions of molecules. Therefore in a solid, with tightly packed molecules, there is a faster speed of sound than in a loosely packed gas (Soundry). This principle is directly reflected in Giancoli's estimated values of the speed of sound in glass (4500 m/s), water (1440 m/s), and in air (343 m/s). Therefore, I hypothesize that as density increases, the frequency will also increase, because in denser liquids the molecules are more tightly packed, resulting in a faster velocity. Since f = v/l as velocity increases, so will frequency (Giancoli). In this experiment, frequency is defined as the compressions per second, measured in hertz, of the sound wave (Couper).
The student has a wine glass that he intends to fill to the some unspecified depth with sugar solutions of different densities. He intends to plot the frequency of the fundamental vibration when the filled glass is excited to resonance by rubbing with a wet finger, against the density of the solution. He has tried to make his work more worthy by paraphrasing a number of text book writer's comments, almost all of which are irrelevant. The presence of the liquid adds mass to the system, reducing the acceleration of the oscillating glass wall, and consequently lowering the frequency of oscillation.
The reference to the glass harmonica is interesting. It could be included if some way could be found to make it relevant, otherwise, the attempt should be abandoned and a new shorter introduction written, that contains relevant background information. Ed.
4 Enzyme action as a function of concentration
From a chemistry report
The hypothesized outcome proved in our experiment proved to be incorrect. Based on universally known and proved theories the prediction that the pH nearest to neutral, where the enzyme's reaction is sped up turned out not to be the case in this experiment. The highest pH of 11 had a very high reaction rate, compared to a low reaction rate of that of the pH of 8. The reaction of the pH level of 3 agreed with the hypothesis, and had the lowest reaction rate of all. A conclusion could be made that catalayse prefers base over acids since the two bases had higher reaction rates. However, according to "Science Education Partnerships" this is not the case. Enzymatic reactions should be the greatest at neutral or at those pH levels closest to neutral.
The writing is spoilt by repetition and the use of clumsy words (first sentence): zero phrases and slang (second sentence): poor syntax (third sentence): the anthropomorphic fallacy (fourth sentence), and the use of however and should in the final two sentences.
A rewrite has been attempted ...
Enzyme activity is expected to be progressively reduced in a solution when the pH is increased or decreased from 7 (neutral). [Insert reference]. The measured reaction rates for catalayse in solutions with pH values of 3, 8, and 11 contradict this assertion. The reaction rate was found to increase with increasing pH (see Graph 1).
... at least that is what I think he meant. Ed.
5 Balls falling in water
The introduction to a report of measurements of the terminal velocities of steel balls falling in water as a function of the radius.
Many people have fed fish before and will realize that fish food is very light. When it's dropped in the water, the food falls down very slowly or floats in water sometimes. However if a rock is dropped, it is clearly differed that the food falls slower than the rock, which shows that denser things fall faster in water than lighter things. The water resistance can also act like air resistance and decrease the velocity of object that has large cross sectional areas. From previous cup cake cup research, the cup with large cross sectional area had smaller terminal velocity than cup with smaller cross sectional area. The purpose of this experiment is to determine the relationship between radius and the terminal velocity of steel balls falling in water. From experience, the terminal velocity of the ball will be smaller as the cross sectional area of the ball gets bigger and the terminal velocity of the ball will be bigger as the mass of the ball gets bigger. The terminal velocity of the ball will be measured with steel balls with same density and the data will be graphed.
The writing lacks directness and clear purpose. The measurements are to be made with balls of the same density. The terminal velocities of bait sinking in water with and without a lead sinker are very different, but the point is not relevant to the task in hand. The paper cup measurements could be relevant, but only if mass of the cups was proportional to the radius cubed, and if paper cups can be considered to be spheres.
A more relevant example is required. For instance, sand and stones thrown into water at the same time. The stones reach the bottom first. It would not be relevant to write about the sedimentation rates of clay particles in water as a function of radius because they fall at very low speeds, in laminar flow. Steel balls with radii greater than one mm fall in turbulent flow. Ed.
6 The title and introduction to a research report. The temperature increase in a rubber strap after repeated stretching and contraction was measured. The temperature increase was plotted against the work done on the rubber as it was stretched.
Energy Lost as Heat of Rubber
Introduction
The purpose of this lab is to figure out the relationship between the amounts of energy lost in the form of heat when a piece of rubber is stretched different distances.
Robert Hooke discovered that when force is exerted on an object, the object can be compressed, stretched, or bent. Any object that restores to its original state (equilibrium) after the removal of applied force, the object is said to be elastic. If the object does not restore to its equilibrium, it is plastic. However, elastic objects have their elastic limits where once more force is exerted onto the object the deformation will remain. Hooke's Law of elasticity states that many materials extend in proportion to the force applied. The law applies to linearly elastic, or Hookean objects, including steel bars, rods, wires, springs, diving boards, rubber bands, and other things. Hooke's law is then:
F = ks According to the Hooke's principal, any elastic object that is stretched or compressed by a force F is deformed by a distance s, which is proportional to the force. The elastic constant k is determined by the nature of the material, therefore turning the proportionality of F and s into equality. It is a measure of the hardness of the deforming object where a large k represents higher rigidity.
The passage fails for many reasons.
The title is uninformative. What is "heat of rubber" and how can it be "lost"?
The first sentence (The purpose of this lab is to figure out the relationship between the amounts of energy lost in the form of heat when a piece of rubber is stretched different distances. ) contains slang and zero phrases, which might be overlooked, if the statement described the measurements to be made. When work is done to deform rubber, the rubber is warmed. A student can confirm this by stretching a rubber band and immediately placing it against the forehead. It feels warm. If the rubber band is then allowed to contract, it feels cold. In this case the student made temperature measurements after many repeated extension-contraction cycles. The sentence, as it stands, gives no information about what was actually done.
Robert Hooke did not discover that objects are compressed, stretched, or bent, when a force is applied. That distinction belongs to a dinosaur in the long distant past. The extent to which that discovery can be said to have occupied the conscious mind of that long dead creature is the subject of ongoing debate. This passage is about physics, not evolutionary psychology, but there is a very strict requirement to avoid the absurd.
Note: Robert Hooke was appointed secretary of the Royal Society in 1677. Newton and Hooke spent 30 years feuding, until Hooke's death in 1703. Hooke believed (correctly in hind sight) that Newton's published work in optics was deeply flawed, which Newton could not accept. Newton's often quoted statement: "If I have seen further it is by standing on the shoulders of Giants" was a nasty comment aimed at Hooke, who was a deformed dwarf. Newton himself is believed to had stood at five foot five inches in his hose.
The next sentence is grammatically incorrect. (Any object that restores to its original state (equilibrium) after the removal of applied force, the object is said to be elastic.) The definition of elasticity is also incorrect. Elastic bodies deform and return to their original condition without the generation of heat. Steel springs are elastic, rubber bands exhibit hysteresis and are not. The subsequent formal discussion is irrelevant. Rubber is not elastic. If it were, there would be no temperature change.
We speak of Newtonian mechanics, but I have not previously seen springs referred to as Hookean! The equation that bears Hooke's name (F = kx) applies to steel springs where x is the extension and k is the spring constant in Newtons per meter. The definitions of the symbols are correct in the text, but they are buried in the next paragraph. Hooke's equation does not apply to rubber bands.
The final sentence (It is a measure of the hardness of the deforming object where a large k represents higher rigidity.) defines hardness in terms of the spring constant k. The definition fails, because a weak spring with a low value of k may be made from the same steel as a stronger spring with a higher value of k. The value of k has nothing to do with the hardness of the metal.
A more appropriate introduction would discuss hysteresis in rubber. It might mention the temperature rise of car tires as they are repeatedly deformed when driven at speed on the road. It might then go on to discuss how this effect could be measured with the instruments available.
7 The acceleration of a ball rolling down a ramp
Conclusion
The outcome of the lab weakly supported the hypotheses that the relationship between acceleration and the angle of the ramp is a sinq. relationship.
In the linear graph one point does not even hit any of the three slope lines and three points barely touch the original linear fit line. The data from the trials do not form a strong sinq. relationship. Results from graph two say that the acceleration of the ball rolling down the ramp should be: (6.5.±.0.4).sinq.+.(0.0.±.0.1). This equation makes sense because the slope value (6.5) should be less then the gravitational force (9.81 m/s2) because some of the force was used to start the ball rolling. The y-intercept should be 0 and the equation calculated was 0, this is within the error bars. The original equation found a=g (sine) angle from the website.was for a ball rolling down a ramp.
The student has excellent data with errors correctly shown. The line of best fit passes through the origin and the acceleration is proportional to the sine of the incline angle to within ±.5%. The comments about the force being used up and points not hitting the line are colorful, but not good physics.
Rewrite the passage succinctly. The slope of the line is not what was expected. The equation from the web is not correct.