# Recent content by dcosmo

1. ### Physics Predictions/Thoughts

Calculate mass units for beryllium and subtract 2 x the mass units for 4 He. Be: 8.005305 He: 4.002603 x 2 = 8.005206 Subtract them: 8.005305 - 8.005206 = 0.000099 Multiply this value by 931.5 MeV/c^2 = 0.0922 MeV Divide by 2 for each alpha particle = 0.0461 MeV = 46.1 KeV = D
2. ### Fission and Fusion Energy

Fusion - like the reaction on the sun: Think of this as smaller type atoms / isotopes with small atomic number (< mass number 56 iron) fusing together releasing massive amounts of energy. Fission reactions occur when the nucleus of generally unstable isotopes are split into smaller, more...
3. ### HSC Chemistry Exam Solutions / Thoughts

Aboriginal and Torres Strait Islander
4. ### HSC Chemistry Exam Solutions / Thoughts

DeltaH is always negative as combustion is an exothermic reaction....
5. ### Has anyone else observed the completely changed Physics 2019 formula sheets?

No, that is the formula sheet that has been used for the past two years. The new one has 2019 "Higher School Certificate Examination" written on the top of it.
6. ### Has anyone else observed the completely changed Physics 2019 formula sheets?

The problem is that students had the old format in their recent HSC trials. They have been using them for around 2 years now. Now 5 weeks out from the actual HSC exam there has been a significant change. There are multiple changed formulae. The equation for gravitational potential energy has now...
7. ### Has anyone else observed the completely changed Physics 2019 formula sheets?

There seems to be 2 versions on the NESA website. The "old" one had the formulae sheet with headers like motion, force & gravity, waves & thermodynamics, electricity & magnetism, quantum, special relativity & nuclear. The new one has a single page of formulae. No headings at all. And the...
8. ### Can DC current create Eddy Currents?

I don't think it matters as long as there's relative motion between a coil or conductor and a magnetic field. That in itself creates an induced current that opposes the change caused by the relative motion in the field. So if a coil is moving from a strong magnetic field to a weaker one, a...
9. ### Thermodynamics question

The base equation to describe this as per the physics formula sheet - Q/t = k * A * DeltaT /d where k = thermal conductivity, A = area, DeltaT is the temperature difference between the heated material and the surrounds. So the rate of heat transferred in watts/sec (Joules) will be proportional...
10. ### Help with Density/Concentration Questions!

13.0mL of ethanol x 0.79 g/mL = 10.27 grams of ethanol. The ethanol will be dissolved into the solution that's been made up to 100 mL. (a) 10.27 g / 100mL of solution (b) 10.27 g/ 100mL = 102.7 g / litre (divide answer (a) by 0.1) (c) Based on 100 ml of solution, (10.27 g / 100 mls) * 100 =...
11. ### Molar Volume Question

Ca(OH)2(s) + CO2(g) - CaCO3(s) + H2O(l) Need to calculate the number of moles of CO2 to start. For this use: PV = nRT - ideal gas law P = pressure (absolute pressure in Pascals), V = volume (litres), n = no of moles of gas, R = universal gas constant, T = temp in degrees Kelvin make...