Lesson Notes By Weeks and Term v4 - SHS 1
INTRODUCTION TO PHYSI CS
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INTRODUCTION TO PHYSI CS
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Subject: Physics
Class: SHS 1
Term: 1st Term
Week: 3
Grade code: 1.1.1.LI.3
Strand code: 1
Sub-strand code: 1
Content standard code: 1.1.1.CS.2
Indicator code: 1.1.1.LI.3
Theme: MECHANICS AND MATTER
Subtheme: INTRODUCTION TO PHYSI CS
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Physics is the study of the world around us, and to study it properly, we must be able to measure things accurately. Imagine a carpenter in Kokompe trying to build a perfectly straight table, a seamstress at Makola Market cutting expensive kente cloth for a wedding, or a pharmacist preparing a prescription. In all these jobs, a small mistake in measurement can lead to big problems! Today, we will learn about the mistakes, or "errors," that can happen when we measure, and how to identify them. Understanding these errors is the first step to becoming a careful and accurate scientist.
This section covers the core knowledge for our lesson. We will explore what errors are and then look at specific errors for each instrument. A. What is an Error in Measurement? An error in measurement is the difference between the measured value and the true or actual value of a quantity. It is important to know that an error is not the same as a mistake. A mistake is a blunder, like misreading the scale (reading 5.2 cm instead of 6.2 cm) or writing down the wrong number. An error is an unavoidable part of measurement due to the limitations of the instrument or the observer. Our goal is to understand and minimize these errors.
There are two main categories of errors: Systematic Errors and Random Errors. B. Systematic Errors A systematic error is a consistent, repeatable error that affects all measurements in the same way. If you measure something multiple times, this error will always be there, either adding to your value or subtracting from it. Cause: Usually caused by a faulty instrument or a flawed experimental design. Effect: It makes the measurement consistently too high or consistently too low. It affects the *accuracy* of a measurement. Example: A clock that runs 5 minutes fast will make every time measurement 5 minutes too long.
Key Type of Systematic Error: Zero Error This is a very common systematic error. It occurs when a measuring instrument does not read zero when the true value is zero. Electronic Balance: If the balance shows a reading of `0.5 g` even before you place any object on it, it has a zero error. Every mass you measure will be 0.5 g heavier than it actually is. Correction: Most electronic balances have a "TARE" or "ZERO" button to reset the reading to 0.00 g before use. Vernier Calliper / Micrometer Screw Gauge: If the zero mark on the vernier scale does not align with the zero mark on the main scale when the jaws are closed, there is a zero error. Positive Zero Error: The zero on the vernier scale is to the *right* of the zero on the main scale. This value must be subtracted from your final reading. Negative Zero Error: The zero on the vernier scale is to the *left* of the zero on the main scale. To find its value, you find which vernier division coincides and use the formula: `Negative Error = -(Total Divisions - Coinciding Division) x LC`. This value must be added to your final reading (since subtracting a negative is adding).