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If you are struggling to get started with vector questions, then try drawing a diagram of what is going on. From the definition of the dot product, we know that 5=a x b x cosΘ With those hints, can you finish it off?

OK, I understand your question. It comes back to the different models of acids and bases. The Arrhenius Model proposes that acids ionise to give H+ ions and bases ionise to give OH- ions. Therefore, under the Arrhenius Model, neutralisation will produce water molecules. The Bronsted-Lowry Model...

I am not going to do the calculation for you, but I will outline the method. Water formation has nothing to do with this problem. In this neutralisation reaction, we are donating a proton to ammonia. There is no water formation. To calculate specific heat capacity, we need three pieces of data...

Whoa. hold on a minute. Let's get this straight, Ka does not change. Ka is a constant for practically any dilution. The only thing that can change Ka is a change of temperature. OK, so what does a change of dilution do to the equilibrium? It changes the percent dissociation of HF molecules, but...

I take your points about taking much of the mathematical theory of electromagnetism for granted in the HSC Physics syllabus. However you can teach everything required by the syllabus in transformers using well-behaved continuous functions like sine or cosine. There is no need to introduce...

Geeze, I hate these questions that are written by supposedly experienced HSC teachers, who have no specialist knowledge of electricity. Yes the best answer is (C) but the graphs for the primary emf and secondary emf are wrong. The actual graphs for emf would look like this: When the switch is...

The equations you used are the correct equations, but, you need to recognise the question refers to speed, and not velocity. Speed is always a positive number. Speed doesn't have a direction, it is not a signed quantity. Kinetic energy is also a scalar quantity, so it doesn't have a direction...

Are you referring to this part? "Calculate the Ksp of KCl at 60o C if the density of the solution is 1.2 g/mL" Pure water solvent has a density at 60o C of 1.0 g/mL. Therefore the extra 0.2 g/mL is the mass of the solute KCl. Convert that extra 0.2 g into moles of KCl solute. Convert the solute...

You haven't given the number of marks allocated to this question, but from the looks of the limited data, it is probably a 3 or 4-mark question. By the way, there are errors in the data. (1) Propane cannot be sourced from natural gas. (2) Methane is the main component of natural gas, so the...

A big part of the problem is shortage of qualified teachers, so schools shy away from resourcing this subject and they don't encourage students to consider it. I think it is an engaging subject for both City students and Country students, with excellent career prospects. Decades ago, this...

To be honest, I'm not sure why so many students try to memorise the solubility rules (and let's face it, they aren't consistent, because there are so many exceptions). The data is given to you in the examination, in the form of the Table of Solubility Constants. Sure, it is useful to be able to...

Did you do HSC Engineering Studies? (the 2 unit course) There is a very useful module in there on civil structures.

You will need the Periodic Table as a general reference for any question about nuclear transmutation (Module 8). You could be asked to write a nuclear transmutation equation, such as the fission of uranium-235 (Z=92) into strontium-94 (Z=38 ) and xenon-140 (Z=54), so you will want to refer to...

(A) is the correct answer. The significant feature of the three graphs is the sudden change of slope at t=2 min. The rates of change of all three species increased (by roughly x2 or x3) and the position of equilibrium is attained much more quickly. This is what a catalyst would do.

The heating power of eddy currents comes the conversion of electrical energy into heat. The rate of heating comes from the product of the current I squared times the resistance R. The equation is Power P = I2R. The magnitude of the eddy current I comes from the rate of change of magnetic flux...

The E-field vector always points in the direction of the force experienced by a positive test charge, placed at that point in the field. Case (a) the negatively charged particle will accelerate to the left, thus increasing its speed and its kinetic energy. Case (b) the positively charged...

The solubility of CO2 (g) in water is highly pH dependent. At low pH, the solubility of CO2 (g) is low. At high pH, the solubility of CO2 (g) is high. In fact, sodium hydroxide solution can be used to sequester CO2(g) from the atmosphere.

Essentially, use the Sum of the Turning Moments = 0 for static equilibrium. Choose the obvious turning point, which is "B". Also note that when the beam starts to lift, the reaction at support A will be zero. First Step. Identify the forces. 20 metres of u.d.l. on the l.h.s. of the fulcrum, 4...

Yes, I share your pain. These words are more often than not used incorrectly. We have to be so careful to define words like precision, accuracy and uncertainty, but I'm happy to give it a go. Precision means how many significant figures you can give for a result. Accuracy means how close is the...

The reaction shown here is the famous steam reformer reaction, in which carbon reduces water to carbon monoxide and elemental hydrogen. In actual fact, this reaction is carried out over a bed of red-hot charcoal at about 900 Celsius, and the water is introduced as steam.