- Read the question carefully, underline key points like “NOT”
- Do I need to do a calculation, if so check the formula sheet
- Can I eliminate some of the options
- Avoid using a calculator if you can, just make an estimate
- Don’t get bogged down on one hard question, but you do need to spend more time on calculation questions
- Get used to answering all the questions, but don’t do it against the clock in the first practice papers it is more important to be accurate until your speed builds up.
PREPARATION
Before the exam read through the rules of your particular exam from a recent past paper. Work out how much time you have and how many questions there are to complete in the time. Hence calculate the time per question. Having said that some multiple choice questions will take three times as long as others because they involve calculation rather than just memory recall.
Do as many past papers as you have time for, early in your revision plan as they are a great way of finding gaps in your knowledge!
FAST CALCULATIONS BY APPROXIMATION
For calculation questions try to get away without using a calculator. Its a mulitiple choice so you only need to be accurate enough to choose between the option. So you don’t need to put exact values in your formula eg pi is 3, fractions like 347/1200 is 0.3. Where there are large powers of ten do the numbers first then work out the power ten.
See the calculation of the value of acceleration due to gravitation at the surface of the earth. My quick non calculator value is 10 compared with the actual value of 9.81 WOW not bad, and quick and error free!
LEARNING POINT You can save a lot of time and greatly improve your accuracy by using approximate calculations rather than using a calculator. This is very important with MPC’s as you need to work fast and there are definitely no marks for method.
Simple Formula Ratio Question
This is a gas law question, find the formula on the data sheet: PV=nRT.
Note the volume V is kept constant, and n and R are constants so write the equation as a proportional T ∝ V
The amazing, and unintuative answer is that if the volume is halved the the temperature is halved to 150K
The answer is A
LEARNING POINT The answer is not what you would guess!
The reason is that although the volume is halved and the temperature will rise, like a bicycle pump, the gas is then cooled taking energy out of the gas to the point where the pressure is the original value.
More Complex Ratio Question
The escape velocity is the velocity that gives an object sufficient kinetic energy to escape its negative gravitational potential energy.
½mv2 = mV where V is the gravitational energy
BUT we don’t have M the mass of the earth or G the gravitational constant. So the trick in this question is to derive them from the formula for g the acceleration due to gravity, in this case at the surface of the earth:
So the answer is B
LEARNING POINT – if the constants in the question are different to what you have look for other related formulae to derive them.
SEE ALSO:
HOW TO ANSWER LONG A-LEVEL PHYSICS QUESTIONS
Please feel free to comment on this post. Good luck with you exams.