1. Distance
2. Measurement
3. Motion
4. Periodic motion
5. Rectilinear motion
6. SI units
7. Units of measurement

Dear student,

1. Distance- Distance is length of the path covered by a moving object. Its SI unit is meters.
2. Measurement - measurement is the comparision of an unknown quantity with a known fixed quantity.
3. Motion- an object is said to be in motion if it changes its position with time. 
4. Periodic motion- periodic motion is the motion that repeats itself after regular intervals of time. any object executing circular,rectilinear motion can be said to be in periodic motion.
for eg:
1) pendulum of a clock
2)child on a swing
3) water drpping from a leaf
4) earth's motion  etc.  

Kindly ask the other parts in a separate thread.

Thanks and regards.

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