A pendulum is a simple device which shows periodic motion. A simple pendulum consists of a non-magnetic metal ball called bob. This bob is suspended with the help of a string. The open end of the string is tied to a support. Bob of the pendulum is held at a side and released. It starts moving in a to and fro motion. This is called an oscillatory motion. The time taken by the pendulum to complete one oscillation is called time period. This time period is always same with a pendulum having same length. Time period changes with the change in the length of the string.
The string of the pendulum is adjusted to the length, that it completes one oscillation in second and it keeps on moving the clock giving us time. It has been found that a pendulum of about 25 cm length takes exactly one second to complete one oscillation.

Day: Time between two sunrise.
Month: Time between one new moon to the next.
Year : Time taken by earth to complete one revolution of the earth.

Firstly, draw perpendicular lines from point E on x-axis and y-axis.

The two vehicles (C and D) will meet (or cross) each other at 5:00 PM and after travelling a distance of 4 km.

After studying the figure given alongside, 0 or E is moving slower as the slope of distance-time graph of E is less than that of graph D.

Since, the distance covered per unit time for the entire distance covered is not the same, the motion is a non-uniform motion

Given, the average age of children 12 years and 3 months
1 year = 365 days = 365 \(\times\) 24 h                              [ 1 day = 24 h ]
= 365 \(\times\) 24 \(\times\) 3600 s                                              [ 1 h = 36000 s]
12 years = 31536000 s \(\times\)12 = 378432000 s
3 months = 30 \(\times\) 3 days = 30 \(\times\) 3 \(\times\) 24 h = 30 \(\times\) 3 \(\times\) 24 \(\times\) 3600s = 7776000s
So, total age in second = 378432000 + 7776000 = 386208000s

Different types of motion are there and they can be named as follows
(i) Periodic motion
(ii) Rolling motion
(iii) Rotatory motion
(iv) Oscillatory and vibratory motions
(v) Translatory motion

When a body travels equal distance in an equal interval of time, then the body is said to be in a uniform motion.
When a body travels unequal distance in an equal interval of time, then the body is said to be in non-uniform motion.

Speed of the circled car is given by
\(=\frac{Distance\ covered}{Time\ taken}=\frac{100}{10\times 100}\)
\((1\ cm=\frac{1}{100}m)\)
\(=\frac{1}{10}m/s\)

As, we know that
Distance covered by the body = Speed \(\times\) Time
speed = 2 m/s
Time =15 min =15 \(\times\) 60= 900s
So, distance = 900 \(\times\)2 = 1800 m = 1.8 km

As, we know that the speed of a body is given by \(Speed=\frac{Distance\ travelled}{time\ taken}=\frac{240}{4}=60km/h\)

Time period of simple pendulum is given by
\(\frac{Time\ taken}{Number\ of\ oscillations}=\frac{32}{20}s=1.65\)
(i.e. the time to complete one cycle)

(b), (d) and (e) are not correct.