NCERT Solutions for Class 5th Maths Chapter 12 Racing Seconds
Updated on 2026-09-19
About this chapter
A second is a very small piece of time. Say one thousand one out loud — that takes about one second. Blinking your eyes takes less than a second. The thin red hand on a wall clock is the seconds hand . It is the fastest hand: it goes right round the dial in one minute. 60 seconds make 1 minute. 60 minutes make 1 hour. This is the one fact the whole chapter rests on. Watch the seconds hand: after it has ticked 60 little marks it has gone once round, and the minute hand has moved on by exactly one mark. So 1 min = 60 s and 1 hr = 60 min . Time is counted in sixties, not in tens. In money, 10 tens make 100. In time, it is 60 that makes the next unit. So when seconds add up past 60, we carry 1 to the minutes. 40 s + 35 s = 75 s = 1 min 15 s. And when we cannot subtract, we borrow 1 minute and
- Raghav's yoga clocks, time elapsed, and the painting table
- hour format and 24-hour format
- Seconds
- Seconds or minutes? Tick the right cell
- Your own list, and how many you can do in a minute
- Three things to measure with a seconds hand
- Observe the clocks and fill in the blanks
- Add the red hand to the clock on the right
- (c) Minutes and seconds on a double number line
- Adding up times, and finding how long a journey took
Quick revision
| Word | What it means | Where it appears | Example |
|---|---|---|---|
| Second | The smallest unit of time in this chapter; 60 of them make one minute | Page 157, the race stopwatches | Snapping your fingers takes about 1 second |
| Minute | 60 seconds | Page 157, 1 min = 60 seconds | The winner took 1 minute 55 seconds |
| Hour | 60 minutes | Page 161, Conversion of Hours to Minutes | Rani painted for 2 hours 10 minutes |
| Seconds hand | The thin, fastest hand of a clock; one full round = 1 minute | Pages 159 and 160 | Red hand pointing at 6 means 30 seconds |
| Minute hand | The long hand; it moves one small mark when the seconds hand goes once round | Pages 155, 159, 160 | Green hand on 9 means 45 minutes |
| Hour hand | The short, thick hand; it tells the hour | Pages 155, 159, 160 | Blue hand between 5 and 6 means the hour is 5 |
| a.m. | The 12 hours from midnight to noon | Page 156, the time-format table | 05:30 a.m. is early morning |
| p.m. | The 12 hours from noon to midnight | Page 156, the time-format table | 09:35 p.m. is night |
| 12-hour format | Time written with a.m. or p.m. | Page 156, left column | 02:30 p.m. |
| 24-hour format | Time counted straight on from 00 to 23 hours, with no a.m. or p.m. | Page 156, right column | 02:30 p.m. = 14:30 hours |
| Time elapsed (duration) | How much time passed between a start time and an end time | Page 155, question 4 | 09:15 a.m. to 11:30 a.m. is 2 hours 15 minutes |
| Double number line | Two number lines drawn one above the other so matching values line up | Pages 161 and 162 | 1 hr above, 60 min below |
| Estimate | A sensible guess made before measuring | Page 157, Let Us Do | Guess how many hops in a minute, then count |
Exercises
- Raghav's yoga clocks, time elapsed, and the painting table — Let us find out Page 155
- hour format and 24-hour format — Let us find out (continued) Page 15612
- Seconds — School Race Page 157
- Seconds or minutes? Tick the right cell — Let Us Do Page 157
- Your own list, and how many you can do in a minute — In-text Questions Page 158
- Three things to measure with a seconds hand — Let Us Find Page 158
- Observe the clocks and fill in the blanks — Let Us Do Page 159
- Add the red hand to the clock on the right — Draw the Missing Seconds Hand Page 160
- Zainab and Remo, and the hours-and-minutes double number line — Conversion of Hours to Minutes Page 161
- (c) Minutes and seconds on a double number line — Let Us Do Page 1621
- Adding up times, and finding how long a journey took — Let Us Do (continued) Page 162
- Start time, end time and duration word problems — Let Us Do Page 163