Activity 11.3 Let us measure a day! (Pages 178-179). Table 11.2 Finding the duration of a solar day Class 8

Activity 11.3 Let us measure a day! (Pages 178-179). Class 8

Activity 11.3 Let us measure a day! (Pages 178-179) Class 8

Table 11.2: Finding the duration of a solar day

1. Find the average duration of the day. Is it nearly equal to 24 hours? Class 8

Answer:

Calculation of average of 24:00 and 23:59 hours

one hour = 60 minutes:

24: 00 hr. = 1440 minutes

23: 59 hr. = 1439 minutes

= 1440+1439

= 2879 minutes

Average = 2879 ÷ 2 = 1439.5 minutes

Conversion back into hours and minutes:

1439.5 minutes = 23 hours 59 minutes and 30 seconds

The average duration of the day = 23 hours 59 minutes 30 seconds

Yes, it is nearly equal to 24 hours.

2. Why do most Indian festivals fall on different dates every year? Class 8

Answer:

Most Indian festivals follow the lunar calendar, not the regular solar calendar. Since the Moon's cycle is shorter than the Sun's, the dates of festivals shift each year when matched with the solar calendar. That's why Diwali, Holi, Eid, and others fall on different dates annually.

3. When I look at the night sky in early evening, I see some moving stars. What are they? Is their motion also periodic? Class 8

Answer:

Those moving 'stars' are actually satellites or sometimes planets. Satellites reflect sunlight and move steadily across the sky. Yes, their motion is periodic - they follow fixed paths and timings as they orbit the Earth.