CI Advanced Subsidiary Level Physics

Course Code: 9702

Physics 9702AS & A2

The A Levels Physics course:

Resource Materials:

cie.org.ukhttp://www.xtremepapers.net/http://asphysics.edublogs.org/

What is a Physical Quantity

A physical quantity is a physical property of a phenomenon, body, or substance, that can be quantified by measurement.

E.g.:

If the temperature T of a body is quantified (measured) as 300 kelvin this is written T = 300 x K = 300 K where T is the symbol for the physical quantity, and K is the symbol for the unit.

Physical Quantities are of two types:

Base quantities

Derived quantities

Base Quantities

Derived quantities:

The Base Units Concept

For Derived Quantities

When you are asked to write the units of a derived quantity in terms of its “base units”, then you recall its respective formula:

Example: 1. Volume=l*b*h hence base units=m2. Area=l*l hence base units= m3. Speed=distance/time hence base units=m/s

Therefore; as a golden rule, you are just supposed to recall the base units of the 7 base quantities we talked about and the rest would all be provided in the Question.

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Till now, we talked about general units of derived quantities, that’s why we didn’t say that derived quantities have SI units (remember how I said that Volume can have the units of liters, m ,cm ,dm ). Now we will look at the concept of SI “base units” and their nexus with derived quantities.

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A=MD/C The base units of A are Kgmsec /m M=kg D=m Then find the base units of the quantity C. Make C the subject: C=MD/A, C=kg*m/kgmsec /m C=m/sec

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Recall how I said that the units on the LHS and the RHS of the equal sign should be the same: i.e. Suppose

Q1. Units of acceleration.

Q2. Find the units of Force using the formula: F=ma

Q3. Units of Pressure? P=pgh

Labeling Graphs: X axis independent quantity Y axis dependent quantity

I. (Recall speed-time)

Table Columns:

Time

Weight Mass Acc due to gravity

50kgm/s2 5Kg 10 m/s2

Class Test

Convert the following quantities into different SI prefixes. Show your entire working. An answer without working would earn a straight ‘zero’

 Use the symbols for the units in your answer. Use of the standard form where

appropriate will earn you extra credit

 All questions carry 2 marks1.               145.56s to milliseconds (ms)2.              127845.64ms to seconds (s)3.              123923593426.2 microseconds (μs) to seconds (s)4.              67000.75 km to m5.                65.7mm to km6.               85.9km to mm7.              6.7m to μm (micrometer)8.               7800540032.54μm to km9.             7807.089J (joules) to MJ (mega joules)10.           6574.56 MJ to J

After you will be done with the A 'level syllabus, you will be in a position to give a rough estimate of quantities you have studied in your course. ‘

Till now, you can give a rough estimate of quantities like:

height of the door?diameter of pencil / pencil lead volume of brick / liquid in drinking cup mass of brick / person / nail time between your hiccups?

Just to give you a feel of what kind of estimate questions you can see in your past papers:

May/June 2008, Paper 2, question 1

Thank you

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