Chapter: 03. Physical Quantities And Measurement 2
Answer in One Line
What is time defined as?
Time is defined as the interval between two events.
What is the main purpose of measuring time accurately?
The main purpose of measuring time accurately is to schedule and coordinate our daily activities effectively.
Name three early instruments used to measure time.
Three early instruments used to measure time include the water clock, candle clock, and sand clock.
Why is it mandatory to mention a.m. or p.m. in the 12-hour clock convention?
It is mandatory to mention a.m. or p.m. in the 12-hour clock convention to indicate whether the time is before or after midday.
How do you convert a time greater than 1200 hours from 24-hour format to 12-hour format?
To convert a time greater than 1200 hours from 24-hour format to 12-hour format, you subtract 1200 from the 24-hour format time and add “p.m.”.
What is the significance of Caesium in atomic clocks?
Caesium is a soft silvery metal used in the most accurate atomic clocks because it provides stable vibrations necessary for precise time measurement.
Besides kelvin, name two other commonly used units of temperature.
Two other commonly used units of temperature are degree Celsius (°C) and degree Fahrenheit (°F).
What is the primary use of a laboratory thermometer?
A laboratory thermometer is primarily used to measure room temperature or the temperature of solids and liquids in a laboratory setting.
Why does mercury appear as a shiny thread in a thermometer’s capillary tube?
Mercury appears as a shiny thread in a thermometer’s capillary tube because of its metallic and reflective properties, making it easily visible for reading.
What is the typical temperature range of a clinical thermometer?
The typical temperature range of a clinical thermometer is from 35° C to 42° C (or 95° F to 108° F).
How does a constriction in a clinical thermometer help in taking a reading?
A constriction in a clinical thermometer helps by preventing the mercury level from falling back into the bulb immediately after the thermometer is removed, allowing time for an accurate reading.
How should a mercury thermometer be disposed of if it breaks?
If a mercury thermometer breaks, it should not be thrown directly into the dustbin due to mercury’s harmful nature, and its disposal should follow specific guidelines for chemical waste.
What is the fundamental difference between heat and temperature regarding their nature?
Heat is a form of energy related to the motion of constituent particles, while temperature is the degree of hotness or coldness of a body.
What is the condition required for heat transfer to occur between two bodies?
Heat transfer can only take place when there is a difference in temperature between the two bodies.
Where does heat transfer from in relation to temperature?
Heat transfer takes place from a body with a higher temperature to a body with a lower temperature.
Who invented the first modern mercury thermometer with a standardized scale?
Daniel Gabriel Fahrenheit invented the first modern mercury thermometer with a standardized scale.
What is the primary purpose of the International System of Measurement?
The primary purpose of the International System of Measurement is to provide a standardized unit of measurement globally for consistency in science, industry, and commerce.
What does each pulse represent when measuring pulse rate at the wrist?
When measuring pulse rate at the wrist, each pulse represents one heartbeat.
How is the average pulse rate of students in a class calculated?
The average pulse rate of students in a class is calculated by adding the pulse rates of all the students and dividing the sum by the total number of students.
Why does your pulse rate usually increase after physical activity like hopping?
Your pulse rate usually increases after physical activity like hopping because your body needs more oxygen and nutrients, so your heart beats faster to pump more blood to your muscles.
What is Greenwich Mean Time (GMT)?
Greenwich Mean Time (GMT) is the local time at Greenwich, from where the Prime Meridian passes, and it is used as a global reference point for measuring time.
Explain why it is important to place your eye at the level of the mercury when reading a thermometer.
It is important to place your eye at the level of the mercury when reading a thermometer to avoid parallax error, which occurs when viewing from an angle and leads to an inaccurate reading.
What is the specific purpose of slanting the straw when setting up a sundial?
The straw in a sundial is slanted towards the ‘12’ line at noon to align it with the Earth’s axis, ensuring that its shadow accurately indicates the time as the sun moves across the sky.
What kind of instruments are found at Jantar Mantar that were used for time prediction?
Jantar Mantar contains architectural astronomy instruments such as the Samrat Yantra, which are large sundials designed to accurately predict time and observe celestial movements.
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