MOTION_AND_MEASUREMENT, Tpes of MotionPPT.pptx
- 1. Prepared by : Jyoti Gonsalves TGT (Chem/Bio) A.E.C.S, KAIGA Class 6 Measurement of Length and Motion
- 2. My height is 100 cm. How do people know how far they have travelled? This is done by a term called Measurement. Measurement means the comparison of an unknown quantity with some known quantity The known fixed quantity is called as unit The result of the measurement is expressed in two parts. One part is a number. The other part is the unit of the measurement.
- 3. The length of the pencil is 13 cm The number 13 forms one part (unknown quantity) cm is the unit (fixed quantity) 13cm
- 4. units of • In ancient times, people used non- standard measurement. • Handspan, foot span, finger-length, cubit, arm length are some of the examples. Non-standardunits of Measurement
- 5. Early Units of Measurement Early units of measurement included are: • The length of a foot • The distance of a step • The width of a hand
- 6. • Hand span A hand span is the distance measured by a human hand, from the tip of the thumb to the tip of the little finger. • Cubit The cubit is the measure your elbow to the tip of from your middle finger when your arm is extended.
- 7. Measurement of width using Non standard unit
- 8. Disadvantages of non-standard units of Measurement • Non-standard units are made up of lengths of different body parts. • These lengths can vary from one person to another. • This can create lot of confusion as there would be no uniformity in measurement. Therefore some standard units of measurements are needed that do not change from time to time.
- 9. Standard units of measurements In 1790, the French created a standard unit of measurement called the metric system. For the sake of uniformity, scientists all over the world have accepted a set of standard units of measurement known as the International System of Units (SI units)
- 10. International System of Units (SI units) • Length, weight and time are considered as basic quantities for measurement. • Metre, kilogram, second are some basic units. • There are 7 basic quantities.
- 11. The SI unit of length is a Meter (m) Each centimetre has 10 parts called millimetres (mm) Each meter (m) is divided into 100 parts called centimetres (cm) For measuring large distances we use a larger unit of length called kilometre (km) Different units of measurement
- 12. 1km = 1000 m 1m = 100 cm 1cm = 10 mm
- 13. Rules for writing symbols of units • Symbols for units are usually written in small letters. • Symbols are not written in plural form. • Symbols should not be followed by a full stop unless they are at the end of the sentence. For example: Kilogram is kg, Metre is m, Centimetre is cm, Kilometre is km
- 14. Instruments used for measuring length
- 15. In taking measurement of a length, we need to take care of the following: • Place the scale in contact with the object along its length. • Take the reading from the zero mark of the scale.
- 16. Correct Measurement of Length The scale should be placed in contact and along the length of the object to be measured In Figure (a) the scale is along the length while in (b) it is not straight but skewed.
- 17. Correct Measurement of Length Since zero mark is not visible in the scale, the full mark “1” is chosen as the initial reading. Any other full mark could have been chosen other than “1”.
- 18. • In some scales, the ends may be broken. You may not be able to see the zero mark clearly. • In such cases you should avoid taking measurement from the zero mark of the scale. • You can use any other full mark of the scale. Then you must subtract the reading of this mark from the reading at the other end.
- 19. For example: • The reading at one end is 1.0 cm and at the other end it is 17.5 cm. • Therefore the length of the table is: (17.5-1.0) cm = 16.5 cm
- 20. • The correct position of the eye is important for measurement. • Your eye must be exactly above the point where the measurement is to be taken as shown below. Position ‘A’ is the correct position of the eye. From positions ‘B’ and ‘C’, the readings may be different.
- 21. Measuring the Length of a curved line In the case of a curved line, measurements can be made with the help of a flexible measuring tape or by using a thread as shown The thread can then be straightened and its length can be measured using a metre scale.
- 22. Moving Things Around Us Motion: The change in position of an object with change in time is called motion E.g. moving train, running horse, moving ball Rest: When an object does not change its position with time then it is called state of rest. E.g. a mountain, a book kept on table, a non moving ball
- 23. Motion vs Rest
- 24. Types of motion Linear Motion/Rectilinear motion: When the motion is in a straight line, it is called linear motion. e.g. a car moving on a straight road, a stone dropped from a height, motion of soldiers in a parade.
- 25. Types of motion Circular Motion: When the motion is on a circular path, it is called circular motion. In this type of motion the distance of the moving object from a fixed point remains the same. e.g: the motion of blades of fan, motion of wind vane, motion of hands of a clock.
- 26. Types of motion Rotation: When an object moved around its axis, it is called rotation. e.g. rotation of the earth on its axis, rotation of merry-go-round.
- 27. Types of motion Periodic Motion: When the motion repeats itself after a fixed interval, it is called periodic motion. e.g. motion of a swing, motion of the needle of sewing machine, motion of a string of guitar, motion of pendulum of clock.
- 28. Objects in a combination of Motions A moving ball shows both rectilinear motion as well rotational motion while rolling on the ground. The ceiling fan has both rotational (moving on its axis) as well a circular motion(path along which its blades moves) Moving wheel shows both rotational as well as circular motion.
- 29. Thank you