The large hand of a clock is 42cm long. How many centimeters does its extremity move in 20 minutes?
Answers
Answer:
large hand of a clock=42cm
angle rotated in 60sec=360°
angle rotated in 20 sec=360°×20/60°
teta=2π/3
42x2π/3=28π
extremity=28π
Answer:
88 cm
Step-by-step explanation:
It's given that the large hand of a clock is 42 cm long. And we need to find that how many centimeters does its extremity move in 20 minutes.
In 1 hour it forms a complete circle of 360°. [1 hour = 60 minutes]
For 20 minutes it will be one third of one hour i.e. 120°
[ In short ]
In 60 min = 360°
In 20 min = 360°/60 × 20 = 120°
To find how many centimeters does its extremity move in 20 minutes. We need to find the length of the arc formed by the circular movement of the hand.
i.e.
l = r∅ = 42 × 2π/3
= 42 × 2/3 × 22/7
= 12/3 × 22
= 4 × 22
= 88
Therefore, the extermity of the hand moves 88 cm in 20 minutes.