If physical quantities are measured in different units, then they should be converted to the same units.
Velocity can be measured in km/hour, m/s etc. For instance distance can be measured in miles, kilometres, meters etc.
One can measure the same quantity in different units.
Si derived units Length m Time s Mass kg
These are the only units necessary to describe any quantity.
International System of Units (metric system)
A single unified system of units makes life easier!.
1 mile = 1.6 km 12 inches in a foot, three feet in a yard.
A unit is a standard amount of a dimensional quantity.
Other physical quantities are defined in terms of these base quantities:.
These quantities are the basic dimensions:.
All physical quantities have dimensions: dimensions are basic types of quantities that can be measured or computed.
Examples are: length, mass, time, electric current, magnetic field, temperature, pressure.
Physics is based on measurement of physical quantities 1 light year =9.4×1015 m 1 nanometre =1.0 × 10-9 m.
1-3) Units, Changing units, Significant figures
12 unexcused absences in lecture+recitation Assessment: Gradingįormat for Active Learning Warm up for lectures: Read the text(use a highlighter, if you prefer) Understanding physics (lectures): Answer questions in class Bring lecture notes, textbook… Challenge yourself (homework): Homework Play with physics (lab): Discover with hands-on experience Practice, practice and practice!!!.