# CBSE Class 6 Science Revision Notes Chapter 10

## CBSE Class 6 Science Chapter 10 Revision Notes – Motion and Measurement of Distances

Class 6 Science Chapter 10 Notes – Motion and Measurement of Distances are prepared by subject matter experts from the most recent CBSE (NCERT) books. Students can access these Class 6 Chapter 10 Science Notes to revise the entire curriculum and improve their performance. These notes are easy to understand and will help the students score better in their CBSE exams.

## Revision Notes for CBSE Class 6 Science Chapter 10

### Class 6 Science Chapter 10 – Motion and Measurement of Distances Notes

When a body or object stays still and does not move from its position, it is said to be at rest.

Various forms of transportation are used to move from one location to another. A foot’s length and a finger’s width were once used as standard units of measurement. This caused a great deal of confusion and necessitated the creation of a standardised measurement system. The SI unit, also known as the International System of Units, is widely used around the globe. In SI units, a metre is used to measure length.

The motion of the body in a straight line is referred to as rectilinear motion.

Circular motion is when a body moves in a circle while maintaining its distance from a fixed point.

The motion that repeats after a certain T-hour interval is known as periodic motion.

The two components of an object’s measurement are its unit of measurement and the total number of units it measures.

Conventional Techniques: They provide approximations of measurements.

• Handspan: The distance between the tips of the thumb and the little finger is known as the handspan.
• Cubit: The distance from the elbow to the middle finger’s tip.
• Arm Length: The length of the arm measured from the shoulder to the middle fingertip.
• Arm Length: The length of the arm measured from the shoulder to the middle fingertip.
• Footstep: It is the distance covered in one step.

Drawbacks: Lack of precision because of individual differences.

Why are standard units of measurement necessary?

The standard units, including hand span, foot, footstep, and cubit, varied. They used to be based on a person’s hand, foot, and other body parts, which led to a lot more confusion in measurements.

Standard Units of Measurement: These are the units for accurately and consistently measuring any quantity. Common units of measurement include the length-metre, mass-kilogram, and time-second.

Rules for Writing Unit Symbols

Standard unit symbols are written in small letters.

Plurals are not used when writing symbols.

Motion: The term “motion” refers to the state of a body when its position changes over time.

### Types of Motion

Linear Motion:  According to Newton’s first law, also known as the principle of inertia, a body with no net force acting on it will either remain at rest or continue to move with uniform speed in a straight line. In fact, there is no important distinction between rest and uniform motion in a straight line; they may be regarded as the same state of motion seen by different observers, one moving at the same velocity as the particle, the other moving at a constant velocity with respect to the particle. There are two types of linear motion:

1. Rectilinear Motion: When an object moves in a straight line between two positions, this is referred to as straight line motion. The motion of a child sliding down  a slide is an example of rectilinear motion.
2. Curvilinear Motion: Motion along curved lines is referred to as curved motion. For example, driving a car on a curved road.

Random Motion: A body is said to be in random motion when it begins to move from one position to another and abruptly alters its direction. For example, the motion of insects flying haphazardly in the garden.

Circular Motion: When an object moves in a circular path with respect to its own axis or around a fixed centre, it is referred to as circular motion. The distance between an object and a fixed point that serves as the centre of the motion’s path remains constant.The two types of circular motions are as follows.

1. Revolution: Revolution is the movement of an object around a fixed centre, for example, the orbiting of the Earth around the Sun.
2. Rotation: Rotation is when an object moves around its own fixed axis in a circular motion. For example, the rotating fan, windmill, or other objects’ blades. The axis in the middle controls rotation. In addition, the components connected to the rotating axis are moving revolutionarily.

Vibratory Motion: When an object moves quickly in both directions, it is said to be vibratory. For example, when a guitar string is plucked.

Oscillatory Motion: An object moves back and forth while maintaining a constant speed and the same path. No matter how many oscillations an object performs, the time it takes to complete a single oscillation is constant. An example would be a heartbeat or the pendulum of a clock.

Periodic Motion: When a body’s motion repeats at regular intervals of time, it is said to be in periodic motion. For example, a person’s heartbeat or a clock’s hands.

Non-periodic Motion: When an object’s motion does not repeat at regular intervals of time, it is said to be in non-periodic motion.

Mixed Motion: When multiple motions are present at once, it is known as mixed motion. For example, a bowled cricket ball exhibits both linear and rotational motion.

Resultant Motion: The motion that leads to another type of motion is known as the resultant motion. For example, the linear motion of a bicycle on the road is produced by the wheels of the bicycle rotating about their axis.

Random Motion: Any movement, regardless of sequence or direction, is random motion. For example, a football player on the field or a buzzing bee.

Uniform Motion: When a body travels an equal distance in an equal amount of time, it is said to be in uniform motion. The motion of the pendulum with equivalent amplitude on either side is an example of uniform motion.

Non-uniform Motion: When a body travels uneven distances over an equal period of time, it is said to be non-uniform. For example, the movement of a bus in traffic.

### 1. According to Chapter 10 of Class 6 Science, what distinguishes non-standard measurements from standard measurements?

Non-Standard Measurements: When someone measures something while taking their hands, arms, or fingers into consideration, the measurement is never accurate and reliable because there are individual differences in the length of their hands, arms, and fingers. Therefore, these techniques are known as non-standard measurements.

Standard Measurements: When measurements for the same object are accepted all over the world, those measurements are referred to as standard measurements.

### 2. What are the different types of motions?

Rectilinear Motion: Rectilinear motion is the term used to describe a movement that follows a straight line. For example, a train running on a straight track or vehicles travelling in a straight line on the road.

Circular Motion: Any given object moving in a circular path around the circumference of a circle is said to be in “circular motion.” For example, the circular motion or rotation of the fan is produced if a stone is tied to a string and rotated.

Periodic Motion: Periodic motion is the repetition of a motion by an object after a predetermined amount of time. For example, the motion of a pendulum.

Translational Motion: When all the parts of an object move the same distance in a given time is known as transitional motion. For example, a cycle moving on a track, a man walking on the road, birds flying in the sky.

### 3. Explain when there is a combination of two or more motions.

In some examples, it is observed that the motion of the object may combine one or more motions. This is known as a mixed motion. Some examples of it include the following.

The movement of a rotating ball on the ground demonstrates how the object follows a rotatory motion while also moving straight ahead. As a result, it can also be said to be performing a rectilinear motion.

The wheels of a car can be seen performing a rotatory motion, but since the car is moving straight ahead, it can also be said to be performing a rectilinear motion.