Section III Syllabus - Physics Part 1

Section III is the largest component of your marks, but can also be a daunting task to study. ACER lists the standard level of knowledge as approximately first-year university biology and chemistry, and good year 12 or first year uni physics. I think that even the chemistry and biology could be considered the equivalent of a solid year 12 program like the International Baccalaureate. I'll write a series of articles breaking down the most important concepts in Section III, with links to relevant resources, and link the lot once I'm done.

Don't forget that the Physics questions make up perhaps a quarter of section III of the GAMSAT, and in terms of your score it may not be worth your time to study physics in-depth if you can get better return elsewhere.

- Make sure that you are comfortable with natural laws - gravity, entropy, conservation of momentum and Newton's laws.

- Make sure that your maths skills are up to par and that you can read complex graphs and rearrange equations.

- Memorisation of equations is useful but not required; the only two I have found useful to memorise are f=ma and v=ir. Both are simple, easy to remember and easy to use, but can be applied to many GAMSAT questions.

Units and Scientific Notation

Know the standard units used for weight, distance, time and more. The units on each side of an equation will be the same, just as the number of atoms in a chemical equation will be the same. Also know the common prefixes for these units.

Many GAMSAT questions will use scientific notation for very large or very small quantities.

Quantities can be either scalars or vectors. Scalar quantities just have an amount, such as mass or speed or time; vector quantities also include a direction, such as displacement, velocity, and force. Vector quantities, such as forces, can still be added if they have different directions using trigonometry. The scalar quantity can be used as the length of the line representing the vector and the direction as the angle of the line. When adding two vectors, draw them as two lines of a triangle; the third line will be the resultant vector, or what you would get if you combined the two forces or displacements.

All objects have mass - mass being the amount of matter present in the object while weight is a measure of how much a gravitational force affects that matter. So an astronaut will always have mass, but her weight will vary depending on the astronaut's location: normal on Earth, light on the Moon, and negligible (weightless) in space.

A mass of one kilogram will accelerate at one meter a second when acted upon with a force of one newton. This is about a tenth of the force caused by Earth's gravitational pull, which varies by as much as .5% depending on location, and correspondingly higher acceleration of 9.8ms-2.

As an aside: What weighs more, a pound of lead or a pound of feathers? They weigh the same, however they have different densities. When placed in water, the upwards force on the material is proportional to the volume of water displaced, so the lower density of feathers mean they will float while lead will sink. On the other hand, a pound of gold weighs less than a pound of lead, because precious metals like gold are still measured on the troy weight system.

Newton's laws of motion describe how objects move. The first law is the law of inertia, and states that an object with no forces acting upon it will remain either still or moving in a straight line at a constant speed.
The second law describes f=ma; that the force on an object is proportional to both it's mass and it's acceleration - pushing a small car is a lot easier than pushing a truck at the same acceleration. The third law is often paraphrased as "To every action there is an equal and opposite reaction." This can be seen in low-friction systems such as on ice rinks, where exacting a force by pushing the wall will cause a reactive force pushing you out into the centre of the rink.

All objects have inertia or momentum - momentum is equal to mass times velocity. Momentum is conserved eg in collisions between billard balls or in executive toys.

An impulse is the change in a force over time. Because the change can be the same, a long, slow push can cause as much impulse as a short, hard push - so the change in momentum is proportional to both force and time. Modelling and Newton's laws contains some good information on modelling

The f=ma equations can also be used to calculate projectile motion, such as the physics standards of bullets or cannons fired into the air (don't forget they come down with the same force they went up with, and shooting bullets into the air leads to deaths every year)

The equation f=ma leads to a range of motion equations that can be used in more detail, however these can be derived.

Displacement, speed, velocity and acceleration can all be graphed over time - like cost and inflation, these are derivatives, and care should be taken with constants and signs.