╞╡§¥ Physics SPM 2013 Chapter 1: Introduction to Physics Hoo Sze Yen www.physicsrox.comPage 1 of 8CHAPTER 1: INTRODUCTION TO PHYSICS 1.1Understanding Physics Physics: Study of all natural phenomenon Physics is a branch of science centred on the study of matter, energy, and the connection between them. 1.2Physical Quantities 1.2.1Quantities and Units Physical quantities–quantities that can be measured Basic quantities–quantities that cannot be defined in any other form of physical quantities Derived quantities –combination of basic quantities via multiplication of division Units –standard size for comparison SI Units –internationally accepted units (determined in Paris in a meeting in 1960)–Le Systemé International d’UnitesThe five basic quantities: Quantity Symbol SI Units Units (Symbol) 1.Length l meter m 2.Mass m kilogram kg 3.Time t second s 4.Temperature T Kelvin K 5.Electric current I Ampere A 1.2.2Scientific Notation (Standard Form) A × 10 n where A ≤1 < 10 and n= integer The value of A should always be rounded to 3 or 4 significant numbers.
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7/27/2019 Physics Final Revision - Introduction to Physics 2013.pdf
╞╡§¥ Physics SPM 2013 Chapter 1: Introduction to Physics
Hoo Sze Yen www.physicsrox.com Page 5 of 8
For practice: Go to http://webphysics.ph.msstate.edu/javamirror/ntnujava/ruler/vernier.html
Using vernier calipers:
cm0 1 2
0 5 10
Main Scale
Vernier ScaleThe length of the vernier scale is equal to 0.9 cm.There are ten divisions on the vernier scale, so the differencebetween one division on the main scale and one division on thevernier scale is 0.01 cm
Each scale division on the main scale is equal to 0.1 cm
Therefore, the sensitivity of a vernier caliper is 0.01 cm
How to make a reading:
First, note down the value on the main scale just before the ‘0’ mark on the vernier scale.
Next, observe which mark on the vernier scale is in line with the main scale.
╞╡§¥ Physics SPM 2013 Chapter 1: Introduction to Physics
Hoo Sze Yen www.physicsrox.com Page 6 of 8
Reading the zero error values on vernier calipers:
When the jaws are closed: If the ‘0’ on the vernier scale is after the ‘0’ on the main scale, this is a positi ve zero err or . The value isobtained by taking the reading from left to right.
When the jaws are closed: If the ‘0’ on the vernier scale is before the ‘0’ on the main scale, this is a negative zero err or . The value isobtained by taking the reading from right to left.
Actual reading = Reading taken – zero errorFor example, if the reading taken is 0.64 cm:
If the zero error is 0.02 cm, actual reading = 0.64 – 0.02 = 0.66 cm
If the zero error is -0.08 cm, actual reading = 0.64 – (-0.08) = 0.72 cm
cm0 1 2
0 5 10
0.02
Zero error = +0.02 cm
cm0 1 2
0 5 10
-0.08
Zero error = -0.08 cm
Take the reading from right to left
7/27/2019 Physics Final Revision - Introduction to Physics 2013.pdf
╞╡§¥ Physics SPM 2013 Chapter 1: Introduction to Physics
Hoo Sze Yen www.physicsrox.com Page 8 of 8
Reading the zero error values on a micrometer screw gauge:
When the anvil and spindle are closed: If the ‘0’ marking on themain scale is visible and the position of the thimble is after the‘0’ marking, this is a positi ve zero err or . The value is taken by
reading it upwards.
Zero error = +0.01 mm
When the anvil and spindle are closed: If the ‘0’ marking on the main scale is not
visible and the position of the thimble is before the ‘0’ marking, this is a negative
zero error . The value is taken by reading it downwards.