TIME & CLOCK
Category : 6th Class
Learning Objective
INTRODUCTION
MINUTE SPACES:
The face or dial of a clock is a circle whose circumference is divided into 60 equal parts called minute spaces.
HOURHANDAND MINUTE HAND:
A clock has two hands, the smaller one is called hour hand or short hand while larger one is called minute hand or long hand.
TIME:
(i) In 60 minutes, the minute hand gains 55 minutes on the hour hand.
(ii) In every hour, both the hands coincide once.
(iii) The hands are in a straight line when they are coincident or opposite to each other.
(iv) When the two hands are at right angles, they are 15 minute spaces apart.
(v) When the hands are in opposite directions, they are 30 minutes spaces apart.
(vi) Angle traced by hour hand in 12 hrs = 360°
(vii) Angle traced by minute hand in 60 min = 360°
(viii) If a watch or clock indicates 8:15 when the correct time is 8 : 00, it is said to be 15 min too fast.
On the other hand, if it indicates 7 :45 when the correct time is 8:00, it is said to be 15 minutes too slow.
Example 1:
Flights to Mumbai leave every 5 hours. At the information counter I learnt that the flight took off 25 min before. If the time now is 10 :45 a.m. what is the time for the next flight?
(a) 4:10 a.m. (b) 2:20 a.m.
(c) 4:20 p.m. (d) 3:20 p.m.
Sol. (d) 3 : 20 pm.
Earlier flight took off at 10.45 - 25 minutes = 10:20 a.m. The next flight will be after 5 hours i.e., at 3:20 P.M.
Example 2:
For how many times in a day are the hour hand and minute hand in a straight line?
(a) 20 (b) 22
(c) 24 (d) None of these.
Sol. (b) In 12 hours both hands would be in a straight line 11 times; during 6: 00 - 7:00 both hands would not be in a straight line because at 5 : 55 and 7 : 05 they would be in a straight line. So during a day both hands will be in a straight line 22 times.
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