Advertisements
Advertisements
Question
Answer the following in detail.
Explain by giving two examples of why the measurement of a physical quantity is expressed as a combination of a numeral and a unit.
Advertisements
Solution
To measure a physical quantity, we need to compare it with a known fixed physical quantity of the same kind, i.e., a unit. Hence, the measurement of a physical quantity is always written as a combination of a numeral along with the unit. The numeral specifies the number of times the unit is repeated.
Example :
- Using a centimeter scale, the length of the pencil box is found to be 20 centimeters (cm). 20 cm simply means that the length is 20 times a centimeter. (The centimeter forms the unit of length in a centimeter scale.) Here, the number 20 is the numeral (magnitude) and cm is the unit.
- Using a weighing (kilogram) scale, the weight of the box is found to be 2 kilograms (kg) 2 kg simply means that the mass of the box is 2 times a kilogram. (The kilogram forms the unit of mass in a kilogram scale). Here, the number 2 is the numeral (magnitude) and kg is the unit.
APPEARS IN
RELATED QUESTIONS
Write true or false for a given statement.
The speed 5 ms-1 is less than 25 km h-1.
What is measurement? How is a measurement expressed?
State two characteristics of a unit.
Answer the following in short.
Mention any two advantages of the metric system over traditional units.
Answer the following in short.
Which institution in the world maintains the guidelines for using the SI units correctly?
Tick the most appropriate answer.
Which of the following is a fundamental physical quantity?
Answer the following in detail.
Which is the most suitable unit for measuring the volume of air inside an inflated balloon?
Solve the following numerical problem.
A piece of wire is wound around a pencil 60 times. If the total width of all the turns is 4 cm, find the diameter of the wire.
Define mass Mention its unit.
A physical quantity A is dependent on other four physical quantities p, q, r and s as given below A = `sqrt("pq"/("r"^2"s"^3))`. The percentage error of measurement in p, q, r and s are 1%, 3%, 0.5% and 0.33% respectively, then the maximum percentage error in A is ______ %.
