Question

The difference in the length of a mean solar day and a sidereal day is about
A. 1 minute
B. 4 minute
C. 15 minute
D. 56 minute

Answer 1

Hint
Considering the earth has 24 hours a day, the difference in the length of the solar day and the sidereal day should be calculated. The difference is calculated based on how fast the earth returns to its original position after completing the revolution and rotation.

Complete step by step answer
it is better to know the definitions of the terms that we are going to use in further explanation. The definitions of the solar day and the sidereal day are as follows.
With the sun being at the centre, the time taken by the earth to complete one rotation about its axis is the solar day. Whereas, with respect to the fixed distant star, the time taken by the earth to complete one rotation about its axis, is the sidereal day.
In the case of a sidereal day, the position of the earth with respect to the distant fixed star almost remains the same. But, in the case of solar day, the earth has to rotate a greater angle to get back to the original position due to its revolution around the sun. Considering the earth has 24 hours a day, a 4 minutes difference can be noted. Thus, a total of 4 minutes difference in the length is between solar day and sidereal day.
$\therefore$ The difference in the length of a mean solar day and a sidereal day is about 4 minutes. Thus, option (B) is correct.

Note
In the case of options, the unit might be given in terms of seconds as well. We know that the difference is 4 minutes, if in case, the options are given in seconds, don’t forget to divide the value by 60 to obtain the value in terms of seconds and vice versa.