## SUMMATIVE ASSESSMENT 1 FOR CBSE CLASS 9 (GRAVITATION)

Find below a question bank from the chapter GRAVITATION of class 9. Portions up to the syllabus for Summative assessment 1 only is included. The answers are not published herewith. Students are advised to solve the questions and problems and post the q...

## The SI & CGS unit of time is same .Why?

Almost in all systems of unit second is the unit of time, most probably because, second is the most convenient one, if we look at the guidelines for selecting a unit. For more details refer to the following links http://www.aticourses.com/international_system_units.htm http://www.french-metrology.com/en/history/history-mesurement.asp http://physics.nist.gov/cuu/Units/history.html http://en.wikipedia.org/wiki/Metric_system http://en.wikipedia.org/wiki/Systems_of_measurement Incoming search terms:cgs unit for timeThe SI & CGS unit of [...]

## why in all the system of units time is always in second?

Please tell me why in all the system of units time is always in second? -Pankaj Sharma Incoming search terms:system unit

## Differences between mass and charge

1. Charge is of two types, mass is only of one kind
2. There are two types of forces (attraction and repulsion) between charges, but there is only one kind