2.  Prepared by : Ahmed Omar, Ahmed Hammad, Mark Hany, and Mohamed Khalid Basic units

3.   mass is a property of a physical system or body, giving rise to the phenomena of the body's resistance to being accelerated by a force and the strength of its mutual gravitational attraction with other bodies.  Instruments such as mass balances or scales use those phenomena to measure mass  The SI unit of mass is the kilogram (kg). MASS

4.   For everyday objects and energies well- described by Newtonian physics, mass has also been said to represent an amount of matter, but this view breaks down, for example, at very high speeds or for subatomic particles.  Holding true more generally, any body having mass has an equivalent amount of energy, and all forms of energy resist acceleration by a force and have gravitational attraction; the term matter has no universally-agreed definition under this modern view.

5. Balance Scale

6.   Mass is represented by (M)  Mathematically W=MG where is W is weight, and G is the gravitational force  So M=W/G

7. Mass mathematical form

8.   Time is one of the basic measurements that we use in our lives all the time. As we all know, time has many units but the most commonly used are seconds, minutes and hours. It is wrongly thought that minutes are the basic unit of time.  The basic unit is actually seconds. Seconds are defined as the time interval for a certain number of energy changes to occur in a caesium atom. Caesium’s chemical symbol is Cs. It is one of few metals that are liquid at room temperature. TIME

9.   There are types many devices used to measure time. Perhaps the most common is the quartz clock or watch.  Many think that when a watch or clock has quartz written on it then its brand its quartz but it really means that the watch uses quartz crystals to measure time. There are many other types of clocks like pendulum clocks that use a swinging pendulum. MEASURING TIME

10. A watch that uses Quartz. Quartz crystal. Pendulum clock.

11.  Thank you for watching For teacher /Omar Mobashar