A free falling body moves with constant speed, i.e., speed of earth's gravity. Thus, the stone will have a uniform motion

Slow and fast are relative terms. Slow motion of a body means speed is lower than the other body which is running fast.

Speed of train = 45 km/h
Train to cover 45 km = 1 h
Train covers 350 km = \(\frac { 350 }{ 45 } \) = 7.77 hour

(a) The metallic ball hanging by a wire/string is called bob.
(b) Time to complete 20 oscillations = 35 s
Time to complete one oscillation = \(\frac { 35 }{ 20 } \) = 1.4sec
\(\therefore\)  One oscillation = Time period = 1.4 sec.

A simple pendulum has a small metallic ball called bob suspended from a rigid stand by a thread. The time taken by the pendulum to complete one oscillation is called time period. One oscillation of a pendulum is completed when the bob moves from position O to A and then from A to B and then back to A or from A to B to A.

A sundial consists of triangular metallic plate called gnomon fixed vertically at the centre of a circular plate. The device is placed in the open in such a way that gnomon points in the north-south direction. It works on the principle that as position of sun in the sky changes, the position and length of shadow also changes. These are calibrated with time

Sand clock is a clock used by Romans to measure a constant time called hour. It consists two chambers fitted over one another filled with an amount of sand and it takes exactly one hour to empty a chamber. Once the upper chamber is completely emptied, the chamber is turned upside down to record the time again. It is also called hour glass

By suspending a metal ball with the help of a cotton thread and the other end of the thread can be tied to some different supports, so in this way, we can prepare a pendulum by our own.

Different types of graphs are
(i) Line graph
(ii) Pie chart
(iii) Bar graph

The factors on which the time period of a simple pendulum depend are
(i) Length of the pendulum
(ii) Acceleration due to gravity

Before the discovery of pendulum clocks, sundials, water clocks and sand clocks were used.

In a year, we have 365 days and 1 day = 24 h So, for 365 days, we have 24 \(\times\) 365 h = 8760 h

In a day, we have 24 h
We know that 1 h = 3600 s
So, 24 h = 3600 \(\times\) 24 = 86400s

If an object covers more distance in equal intervals of time with respect to other, then we can say that object is moving faster with respect to the other object.

y-axis represents the dependent variable.