(i) Periodic motion
(ii)Circular motion.

The screw undergoes two kinds of motions, i,e., circular and periodic motions

(i) Length of the scale, that you are using to measure, must be greater than the length of the object.
(ii) The eye must be placed just above the point, that you are reading, otherwise there will be an error due to parallax.
(iii) If the zero mark of the scale is damaged or the edge of the scale is not smooth, then start the measurement from another mark

(i) Linear motion: A car moving in a straight line is an example of a linear motion.
(ii) Circular motion: Motion of blades of fan is an example of circular motion.
(iii) Rotatory motion: Rotation of earth on its axis is an example of rotatory motion

Distance is actually defined as length or space between two places. It is clear from the diagram that when we whirl the stone, the space or length between points A and B, i.e. between hand and stone does not change.
Hence, distance is same.

First of all, take a round pencil and try to wrap the given wire round the pencil making.
25 turns forming a coil. Now, measure the length of the wire that turns formed coil. Divide the total length of the coil by number of turns. This is the thickness of the Wire.

The measurement of a room using foot of different persons will not be equal. This is because foot steps of every person are not constant. Their distance can very time to time.

(a) Priya is intelligent and has good knowledge upto class 6th.
(b) As length measured by Shyam is from measuring tape which is not elastic as of Ram. So, they have different measurements.

We need standard unit of measurements because the unit like handspan, foot, cubit differ from person to person or even indifferent countries. So, for a uniform measurement, standard unit of measurement is really required.

Yes, a person driving a car is in rest with respect to other person in car but in motion with respect to a person standing roadside. State of motion and rest depends upon observer or reference point.

Similarities are given below

(i) The wheels of a bicycle and a ceiling fan execute a rotational motion on a fixed axis.
(ii) The particles of both exhibit circular motion except the particles at the centre.
Differences are given below
(i) Bicycle changes its position while exhibiting circular motion but a ceiling fan does not change its position.
(ii) Bicycle can execute rectilinear motion with translational motion but ceiling fan does not execute rectilinear motion.

Accurate scale r-eading begins from zero as shown below

But here the reading on scale begins with 3 cm
Thus, the error in the scale = 3 cm- 0 cm= 3 cm
Now, the other end on the scale reads = 33.1cm
Thus, the actual length of the needle = (Reading on the other end - Error reading of first end)
= 33.1 cm - 3 cm = 30.1 cm

We know that
1 kilometre (km) = 1000 metre (m)
1 metre (m) = 100 centimetre (cm)
1 centimetre (cm) = 10 millimetre (mm)
Hence, increasing order of given units is as follows:
1 millimetre <1 centimetre <1 metre <1 kilometre

A pace or a footstep cannot be used as a standard unit of length because the length of footstep, forearm length and handspan of different person is different.
Since, standard units must be similar at all places of world and in all kinds of conditions. It should not depend upon body parts and natural phenomenon. So, footsteps and other such measuring systems cannot be use as standard unit.

There are mainly three modes of transport which are given below:
(i) Land transports Those transports that run on land are called land transports, e.g. bus and truck.
(ii) Water transports Those transports that run on water are called water transports, e.g. boat and ship.
(iii) Air transports Those transports that run in air are called air transports, e.g. aeroplane and helicopter.