Textbook Solutions: Motion and Measurement of Distances | Eureka Plus Class 6: Book Solutions, Notes & Worksheets PDF Download

I. Tick (✔) the correct option.

1. 
Ans: (b)

2. 
Ans: (a)

3. 
Ans: (b)

4. 
Ans: (d)

5. 
Ans: (a)

6. 
Ans: (a)

II. Answer the following questions in a word or two.

1.
Ans: The invention of the wheel and axle brought about a great change in the mode of transport.

2.
Ans: The units of measurement accepted everywhere are known as SI units (International System of Units).

3.
Ans: Millimetre is the SI unit used to measure a small piece of thread.

4.
Ans: An object is at rest if there is no change in its position.

5.
Ans: The SI unit for measuring length is the metre.

III. Write the kinds of motion(s) each of the following show(s). 

1.
Ans: Circular motion

2.
Ans: Rotational motion

3.
Ans: Oscillatory motion

4.
Ans: Random motion

5.
Ans: Translatory motion

6.
Ans: Translatory motion

IV. Answer the following questions in one sentence. 

1.
Ans: The SI unit used to measure the size of a room is the meter (m).

2.
Ans: Kilometer (km) is used to measure large distances.

3.
Ans: Motion is when an object changes its position with time.

4.
Ans: Translatory motion is when an object changes its position with respect to a stationary point or object.

5.
Ans: Oscillatory motion is when an object moves to-and-fro between any two points.

V. Answer the following questions in two sentences. 

1.
Ans: The advantages of using SI units include consistency and uniformity in measurements worldwide, making it easy to compare and standardize measurements. For example, a bulb manufactured in any country using SI units will have the same size and performance characteristics.

2.
Ans: Random motion differs from rectilinear motion in that random motion lacks a defined or predictable path, whereas rectilinear motion involves movement in a straight line or along a specific path.

3.
Ans: Periodic motion is motion that repeats itself in a fixed time interval. For instance, the hands of a clock exhibit periodic motion, with the hour hand completing a circle in 12 hours and the minute hand completing a circle in 60 minutes.

4.
Ans: The motion of the Earth around the sun is a periodic motion known as a revolution. It takes the Earth 365 days and 6 hours to complete one revolution around the sun.

VI. Answer the following questions in four to five sentences. 

1. Distinguish between circular motion and oscillatory motion with the help of simple diagrams.
Ans: 

2.
Ans: When writing SI units, several rules need to be followed:

• Rule 1: The symbol of a measuring unit is written in small letters, but if it is named after a scientist, it is written in a capital letter. For example, Metre = m, joule = J.
• Rule 2: When the full form is used, the symbol is written in small letters, even if it's named after a scientist. For example metre, kilometre, joule.
• Rule 3: A symbol for a unit is never written as a plural, but when the full form is used, it may be written in plural. For example, "The length of a box is 10 m." or "The length of the red box is 10 metres."
• Rule 4: The symbol is never written with a full stop unless it appears at the end of a sentence. For example, "The road is 10 m wide." or "The length of the pole is 1 m."

Think and answer

1. 
Ans: 
The motion of bird A is a straight-line or rectilinear motion since it's flying directly from its starting point to point 'C'.
The motion of bird B is a curvilinear or curved path since it's flying in a wavy pattern before reaching point 'C'.
If both birds reach point 'C' at the same time, bird B flew faster because bird B covered a longer distance (due to its curved path) in the same amount of time that bird A covered a shorter, straight-line distance. In order to cover that longer distance in the same timeframe, bird B must have had a greater speed.

2. 
Ans:
To find out the total length of thread required to repeat the design 10 times on cloth, you can follow these steps:
Measure the length of the thread required for one iteration of the design on the cloth.
Multiply that measurement by 10.
However, the image doesn't provide any scale or units for measurement. A simple method without direct measurement tools would be:
Use a piece of string or thread and trace the design once.
Measure the length of the string or thread used.
Multiply that length by 10.
That will give you the total length of thread required to repeat the design 10 times on cloth in cm.

3. 
Ans: The mouse that followed the straighter (red) path from point A to B and back to A took a shorter distance compared to the mouse that took the more elongated (black) path.
Given that both mice moved with the same speed, the time taken to cover a distance is directly proportional to the length of the path. The longer the distance, the more time it takes, and vice versa.
Therefore, the mouse that followed the straighter (red) path must have taken less time because it traveled a shorter distance than the other mouse.