Question

The minute hand of a clock is 15cm long.How far does the tip of the hand move during 40 minutes?

Answer 1

Answer:

in 40 minutes minute hand needle will rotate by an angle=360*40/60=240 degree=240*pi/180

=4pi/3 radian

so tip will move =r* theta

=1.5*4pi/3

=2pi c.m.

Answer 2

Answer:

$20\pi$

Step-by-step explanation:

Given :The minute hand of a clock is 15 cm long

To Find:How far does the tip of the hand move during 40 minutes?

Solution:

60 minutes = 360°

1 minute = $\frac{360}{60}$

40 minutes = $\frac{360}{60} \times 40$

                   = $240$

Convert it in radians

240°=$240 \times \frac{\pi}{180}$  radians

240°=$\frac{4\pi}{3}$  radians

Now  the tip of the hand move during 40 minutes = $r\times \theta$

                                                                                    = $15\times \frac{4\pi}{3}$

                                                                                    = $5\times 4\pi$

                                                                                    = $20\pi$

Hence the tip of the hand move during 40 minutes is $20\pi$