Time can be defined as the dimension based on which the evolution of any system takes place. It can be measured in terms of seconds, minutes, hours, days, weeks, months, and years.
The SI unit of time is seconds.
Number of seconds in a day
Let us calculate How many seconds are in a 24 hour day
We know that
1 minute 60 seconds
1 hour =60 minutes
60 X 60
= 3600 seconds
1 day (24 hours)
=3600 X 24
Hence there are 86,400 seconds in a day