Question

the minute hand of a clock is 20 cm long how far does the tip of the hand move in 2 hours

Answer 1

radius of circle = minute of clock = 20cm

one revolution = 1 hour = pi*r*r

22/7*20*20 = 8800/7 = 1257.14

two revolution = 2 hours = 2 * 1257.14



= 2514.36 

thanx 

Answer 2

in 2 hrs the hand will rotate twice.
therefore the tip would travel 2 times the circumference...
$2 \times 2\pi r \\ = 4 \times \frac{22}{7} \times 20 \\ = 1760 \div 7 \\ = 2514.28571428571428571$