Physical Quantities And Measurement Techniques
Overview
Every number in physics is only as good as the measurement behind it. Before you can talk about speed, force or energy, you have to be able to measure length, volume and time reliably, and know whether a quantity carries a direction or not. This is the toolkit the whole subject is built on.
In this lesson you will choose the right instrument for a length, a volume and a time interval, use a clever multiple-measurement trick to pin down a tiny distance or a short time accurately, and sort quantities into scalars and vectors. You will also learn to combine two vectors at right angles, a skill examiners test again and again.
Objectives
- Describe the use of rulers and measuring cylinders to find a length or a volume
- Describe how to measure a variety of time intervals using clocks and digital timers
- Determine an average value for a small distance and for a short interval of time by measuring multiples (including the period of oscillation of a pendulum)
- [Supplement] Understand that a scalar quantity has magnitude (size) only and that a vector quantity has magnitude and direction
- [Supplement] Know that the following quantities are scalars: distance, speed, time, mass, energy and temperature
- [Supplement] Know that the following quantities are vectors: force, weight, velocity, acceleration, momentum, electric field strength and gravitational field strength
- [Supplement] Determine, by calculation or graphically, the resultant of two vectors at right angles, limited to forces or velocities only
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Lesson Evaluation
Congratulations on completing the lesson on Physical Quantities And Measurement Techniques. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- Which instrument is most suitable for measuring the volume of a liquid? A. metre rule B. measuring cylinder C. stopwatch D. balance Answer: B
- A student times 20 swings of a pendulum as 24.0 s. The period is: A. 24.0 s B. 4.8 s C. 1.2 s D. 0.83 s Answer: C
- Which of these is a vector quantity? A. mass B. temperature C. velocity D. energy Answer: C
- Forces of 6 N and 8 N act at right angles on a point. The resultant is: A. 2 N B. 10 N C. 14 N D. 48 N Answer: B
- Timing many swings instead of one mainly improves the measurement by: A. increasing the period B. removing parallax C. sharing the reaction-time error over many swings D. changing the pendulum length Answer: C
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