Motion and Measurement Test - 1

The length of the needle = 33.1 - 3.0 = 30.1 cm

a. The length of the scale that is used to measure an object can be less than the length of the object. All the readings can be added to get the total length.
b. The eye should be placed just above the points that you are reading, otherwise there will be error due to parallax.
c. If the zero mark of a scale is damaged or edge of the scale is not smooth, then start measuring from another mark.

Moon revolving around the Earth - Circular motion and Periodic motion
Falling of a stone - Rectilinear motion
Motion of a child on a swing - Periodic motion
Vibrating strings of a guitar - Periodic motion

(A) Metre - SI unit of length
(B) Millimetre - Unit used to measure very small distances
(C) Hand span - Non-standard unit of length
(D) Kilometre - Unit used to measure large distances

Length of one part of the thread = 14.3 - 1.0 = 13.3 cm
So, the total length of the thread = 5 × 13.3 = 66.5 cm
1 cm = 10 mm
Hence, total length of the thread = 665 mm

In rectilinear motion, each particle of the body moves in the same direction and with the same speed. So, statement B is correct.
Motion of the second hand of a clock is an example of the rotational motion. So, statement A is incorrect.

Periodic motion is the motion which repeats itself after fixed interval of time. To and fro motion of the particle is oscillatory motion which also repeats itself after fixed time interval. Circular motion is a motion which repeats itself after fixed time interval. Hence, all of the above are examples of periodic motion.

Beating of heart is a periodic motion as it repeats itself after fixed time intervals. Motion of the seconds hand of a clock is an example of the rotational motion. The points on the rim of a rotating wheel move in a circular path, hence only statement (b) is correct.

In veena, strings move up and down between the two fixed points. Hence, we can say that motion of the string is vibratory and periodic.