Motion and Measurement of Distances: science class six
NCERT Exercise Solution
Question (1) Give two examples each, of modes of transport used on land, water and air.
Answer
Modes of transport on land: Motorcycle, Car
Modes of transport on water: A boat, A ship
Modes of transport in air: An aeroplane, A helicopter
Question (2) Fill in the blanks:
(i) One meter is ________ cm.
Answer
One meter is 100 cm.
(ii) Five kilometre is _____ m.
Answer
Five kilometer is 5000 m.
(iii) Motion of a child on a swing is _________.
Answer
Motion of a child on a swing is Periodic Motion.
(iv) Motion of the needle of a sewing machine is ______.
Answer
Motion of the needle of a sewing machine is Periodic Motion cm.
(v) Motion of wheel of a bicycle is ________.
Answer
Motion of wheel of a bicycle is Circular Motion cm.
Question (3) Why can a pace or a footstep not be used as a standard unit of length?
Answer
A pace or a footstep not be used as a standard unit of length because the length of the pace or a footstep differs from person to person. Hence this will give the difference in measurement.
Question (4) Arrange the following lengths in their increasing magnitude:
1 meter, 1 centimeter, 1 kilometer, 1 millimeter
Answer
1 millimeter < 1 centimeter < 1 meter < 1 kilometer
Question (5) The height of a person is 1.65 m. Express it into cm and mm.
Answer
We know that
1 m = 100 cm
And, 1 cm = 10 mm
Thus, 1 m = 100 × 10 mm = 1000 mm
Therefore, 1.65 m = 1.65 × 100 cm = 165 cm
⇒ 1.65 m = 165 cm Answer
And, 1.65 m = 1.65 × 1000 mm = 1650 mm
⇒ 1.65 m = 1650 mm Answer
Question (6) The distance between Radha's home and her school is 3250 m. Express this into km.
Answer
We know that, 1 km = 1000 m
Therefore, 1 m = 1⁄1000 km
Therefore, 3250 m = 3250⁄1000 km
⇒ 3250 m = 3.25 km Answer
Question (7) While measuring the length of a knitting needle, the reading of the scale at one end is 3.0 cm and at the other end is 33.1 cm. What is the length of the needle?
Answer
Given, initial reading = 3.0 cm
And final reading = 33.1 cm
Therefore, length of the needle = Final reading – Initial reading
= 33.1 cm – 3.0 cm = 30.1 cm
Thus, length of the knitting needle = 30.1 cm Answer
Question (8) Write the similarities and differences between the motion of a bicycle and a ceiling fan that has been switched on.
Answer
Similarities between motion of a bicycle and a ceiling fan
The motion of the tyre or a point on the wheel of a bicycle is in circular motion.
And the motion of the ceiling fan also in circular motion.
Difference between motion of a bicycle and a ceiling fan
The motion of a bicycle can be rectilinear motion when cycle runs along a straight line.
But, the motion of a ceiling fan cannot be rectilinear.
Question (9) Why could you not use an elastic measuring tape to measure distance? What would be some of the problems you would meet in telling someone about a distance you measured with an elastic tape?
Answer
An elastic measuring tape cannot have a fixed length because it can be stretched this can give incorrect measurement of length. So an elastic measuring tape cannot be used to measure a distance.
If a distance is measured using an elastic measuring tape, then I will tell the another person that the measured length would not be correct because the elastic measuring tape does not have a fixed length.
Question (10) Give two examples of periodic motion.
Answer
Two examples of Periodic Motion
(a) Motion of a pendulum
(b) Motion of the needle of a sewing machine
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