Answer:
Science is the systematic study of the natural world through observation and experimentation. It helps us discover facts, laws and principles about natural phenomena.
Question 2
What is a physical quantity?
Answer:
A physical quantity is a measurable property that can be expressed by a numerical value and a unit. Examples include length, mass, time and temperature.
Question 3
What is a non-physical quantity?
Answer:
A non-physical quantity is a quality that cannot be measured directly with scientific instruments or expressed with a standard unit. Love, beauty, fear and wisdom are examples.
Question 4
Differentiate between physical and non-physical quantities.
Answer:
Physical quantities can be measured and expressed with a number and unit, whereas non-physical quantities cannot be measured directly with standard scientific instruments. Length is physical, while affection is non-physical.
Question 5
What are base physical quantities?
Answer:
Base physical quantities are independently selected fundamental quantities that are not defined in terms of other physical quantities. Length, mass and time are examples.
Question 6
What are derived physical quantities?
Answer:
Derived physical quantities are quantities expressed in terms of one or more base quantities. Speed, area, volume, density and pressure are derived quantities.
Question 7
Why is speed called a derived quantity?
Answer:
Speed is called a derived quantity because it is calculated from two base quantities: distance and time. It is expressed as distance divided by time.
Question 8
Define measurement.
Answer:
Measurement is the process of comparing an unknown physical quantity with an accepted standard quantity of the same kind.
Question 9
Why did old units such as hand span and foot cause confusion?
Answer:
The sizes of hands, feet and steps differ from person to person. Therefore, the same object could produce different measurements when measured by different people.
Question 10
What is a unit?
Answer:
A unit is an accepted standard used for measuring a physical quantity. It gives a definite meaning to the numerical value of a measurement.