Introduction
Wherever there is change in position of the object or body we termed it as motion, as they are continuously changing their initial position with respect to time. But when an object or body is not changing its position with respect to time it is said to be in rest position. Example of a rest position is a pen kept on table and for motion is walking on a road. Whereas the case of measurement has different concepts with respect to motion. In the case of measurement we quantify objects or anything. Example: distance of your school from your home.
What is Motion?
Whenever there is movement or change in position of an object or body we termed it as motion.
Example: Moving train, flying aeroplane, etc.
We can classify motion into various types:
1.Rectilinear Motion: When an object moves along a straight line it is called rectilinear motion. Example: person walking on a straight road.
2.Circular Motion: When the distance of the object from a fixed point remains constant, it possesses circular motion. Example: object moving around a circular well.
3.Periodic Motion: When an object moves to and fro about a point it possesses periodic motion.
Example: moving pendulum.
Measurement of Distance with respect to Time
As distance is measured with respect to time we denote it as (T) in dimensional formula.
If in case speed if an object is given and time is also given then from here we can find distance covered by moving objects.
As distance = speed/ time
In terms of S.I unit Meter = Meter per second / Second
So from here we can find a covered distance.
S.I unit of distance is Meter and in dimensional formula we consider S.I unit as dimensional formula is written in the form of (MLT). Here M stands for mass, L stands for length/distance and T stands for time.
Story of Transportation
There is a long story behind transportation. Earlier people used to move only on foot and carry their goods either on their back or by using animals. Whereas for transport along waterways they used boats. Simple wood logs were used for boat formation and they use wood with hollow cavities inside it, so that wood can float on water streams. Slowly and gradually people started learning how to give different shapes to boats. By passing time they invent wheels, which become a grat mode for transportation. Upto 19th century people were totally dependent on animals for transportation purposes. But by the end of the 19th century steam engines were invented which became a great source of power. After this people keep on inventing different modes of transportation.
Measurement History
In ancient times, the length of foot, the width of finger and distance between two different places were commonly measured by different units of measurements.
This was proved by people of Indus valley civilization as because of their good measurement as constructed such a good geometrical monument. Where in ancient Egypt they used cubits from elbow to fingertips and this was accepted as a length all over the world. In some parts of the world people also use feet as a unit of length.
Standard Unit of Measurement
For unique measurement properties, scientists accepted standard units of measurement all over the world. As this unit is now known as the international system of unit i.e (S.I Units). Each different fundamental quantity has different S.I units. S.I unit of length is meter. Each meter is divided into 100 equal divisions known as centimeters(cm). Further each centimeter has 10 equal divisions known as millimeters(mm).
1 meter = 100 centimeter
1 centimeter = 10 millimeter
1 kilometer = 1000 meter
Zero Error and Correct Way to Measure Length
We use different instruments for measurement of different objects depending upon their shape and size. Different ways are there for accurate measurement of an object. Some of these tips are given below:
Scale should be in proper contact with the object which is being measured.
If the scale is broken or the zero mark is not visible then we have to take different points as a zero point for proper measurement of an object.
Your eye should be exactly above the point, where measurement is to be taken.
We will get correct reading if we subtract the value from the full mark considered as zero.
How to Measure a Curved Line
Measurement of curved line can be done by following method:
It is not possible to measure the length of curves by meter scales.
So for measurement of curved line string is used by creating a knot at one end and keeping at the beginning. By this we can measure its length.
After this we have to stretch the length of the string and measure it with the help of meter scale.
Measuring tape can also be used for the measurement of curved objects. Example: length of snake, length of curved landscape, etc.
FAQs on Motion and Measurement
1. What are the core concepts of motion and measurement in Class 6 Physics?
In Class 6 Physics, motion is defined as a change in an object's position with respect to a reference point over time. Measurement is the process of comparing an unknown quantity with a known, fixed quantity called a unit. This chapter explores how we describe movement and the standard methods used to measure distances accurately.
2. Why was it necessary to develop standard units of measurement like the metre?
It was necessary to develop standard units to ensure consistency and reliability. Before standard units, people used non-standard units like the hand span, cubit, or footstep. These varied from person to person, leading to confusion and inaccurate measurements in trade and science. Standard units, like the metre, provide a fixed and universally accepted value, ensuring that a measurement is the same for everyone, everywhere.
3. What are the main types of motion? Please provide examples.
The main types of motion studied are:
- Rectilinear motion: Movement along a straight line. Example: A car driving on a straight highway.
- Circular motion: Movement along a circular path around a fixed point. Example: The tip of a fan blade while it is switched on.
- Periodic motion: Motion that repeats itself after a fixed interval of time. Example: A child on a swing or the swinging of a pendulum.
- Rotational motion: An object spinning on its own axis. Example: A spinning top or the rotation of the Earth.
4. What is the key difference between circular motion and rotational motion?
The key difference lies in the axis of movement. In circular motion, an object moves along a circular path where the axis is outside the object (e.g., the Earth revolving around the Sun). In rotational motion, the object spins around an axis that passes through the object itself (e.g., the Earth spinning on its axis to cause day and night).
5. How can you measure the length of a curved line using simple tools?
You can measure a curved line using a thread and a ruler. First, place one end of the thread at the beginning of the curved line and carefully trace the path of the line with the thread. Mark the point on the thread where the line ends. Finally, straighten the thread and measure the length from its starting point to the mark using a ruler. This gives an accurate approximation of the curved length.
6. What is a parallax error and how can it be avoided while taking measurements?
A parallax error is a mistake that occurs when the apparent position of an object changes due to a change in the line of sight. When using a ruler or a scale, this happens if you view the measurement from an angle instead of directly from above. To avoid this error, you must position your eye directly perpendicular to the measurement mark on the scale.
7. Can an object have more than one type of motion at the same time? Explain with an example.
Yes, an object can exhibit multiple types of motion simultaneously. A classic example is the wheel of a moving bicycle. The wheel itself spins on its axle, which is rotational motion. At the same time, the entire bicycle moves forward along the road, which is rectilinear motion (also called translatory motion).
8. What is the standard SI unit of length, and what are its common conversions?
The standard international (SI) unit of length is the metre (m). It is used worldwide for scientific and general measurements. Common conversions include:
- 1 kilometre (km) = 1000 metres (m)
- 1 metre (m) = 100 centimetres (cm)
- 1 centimetre (cm) = 10 millimetres (mm)
9. How did people measure distances in ancient times before standard units existed?
In ancient times, people used parts of the body as non-standard units for measurement. These included the cubit (the length from the elbow to the tip of the middle finger), the hand span (the distance between the tip of the thumb and the little finger of a stretched hand), and the foot span. While useful for estimation, these units were unreliable because their lengths varied from person to person.
