Coping with calculations

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GCSE Physics By: Please log in to see tutor details
Subject: Physics » GCSE Physics
Last updated: 06/09/2016
Tags: calculation, gcse physics, method

People convince themselves that you need to be good at Maths to be good at Physics, but they are wrong! I would be lying if I said it didn't help but it is far from essential. While teaching I have had experience with students of varying abilities in Maths and it has been interesting to see how they have coped with Physics. I have seen bright Math wizkids struggle on how the numerical information can be used and applied, yet I have also seen students with basic level maths complete A grade questions by following fixed basic steps.

Firstly you need to know what information is in the question. Each number will have a descriptor in front, eg "the plane had a velocity of 260m/s", the descriptor in this is velocity. This gives you the first piece of information to answer the question. Lets look at a generic example.

OCR - June 2014

"Alice drops a pebble from the top of a high cliff. The mass of the pebble is 0.30 kg. Calculate the momentum of the pebble when it is falling at a velocity of 4.0 m/s"

The first thing you should do is look for the numbers and the descriptor in front of it. This would give us

mass of the pebble is 0.30 kg   and also    velocity of 4.0 m/s

Don't forget the thing we're trying to calculate. Calculate the momentum

The next stage is to go through your equations and find one with, massvelocity and momentumYou will find that the relationship between them is

momentum = mass x velocity

next we put in what we know, mass = 0.30 kg and velocity = 4.0m/s

momentum = 0.30 x 4.0 = 1.2kgm/s

This method is perfect for answering basic level math questions. They can make it harder by not including the descriptor, the question below shows an example of this. The majority of the numbers will be followed by a unit which is even more useful than the descriptors are, eg velocity has the unit m/s and momentum has the unit kgm/s. Lets have a look at the question below. 

EdExcel - March 2013

"The magnet is made to spin at a steady speed. The ammeter gives a reading of 1.5 A. The voltmeter gives a reading of 6 V. Calculate the output power of the generator".

When we take out the numbers now, they will not have descriptors but they will have units.

1.5A    and also    6V      and we are trying to calculate the output power of the generator.

Over time of practicing questions you will learn that A (amps) measures the current and V (volts) measures the potential difference. Using what we know we need to find an equation with currentpotential difference and power

Looking through your equations you will see that

power (W) = potential difference (V) x current (A)

power (W) = 6V x 1.5A = 9W

This is everything that you will be expected to do as for the maths in a foundation Physics exam. Obviously it gets easier the more you do it which is why Physics text books have the same style of questions multiple times, just for practice.

I hope this has been useful for you and I wish you all the best in your Physics GCSE!

Chris Hanson A-level Physics Tutor (Manchester)

About The Author

Hi, I'm Chris and I am a fully qualified teacher of Physics with great passion and enthusiasm for the subject. I always endeavour to relate topics to current events and give them real life context to make it more engaging and memorable for students.

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