Question

Rohit is preparing for X board examination. To manage the time, he observes clock again and again. One day, he focus again and observed the short and long hands of a clock are 5 cm and 7 cm long respectively. He wanted to calculate the distance travelled by short hand in 48 hours is:​

Answer 1

Step-by-step explanation:

as the short hand of the clock travels in a circle, 48 hrs means 2 revolutions.

circumference of 1 revolution = 2piR

for 24 hrs, the distance traveled= 2×pi×5

=10pi

for 48 hrs, distance = 20pi

Answer 2

Given: Length of the short arm of the clock = 5cm

Length of the long arm of the clock = 7cm

Time for which distance has to be calculated = 48 hrs

To Find: Distance covered in 48 hrs

Solution:

We know that the short arm of the clock shows the hours and the long arm of the clock shows the minutes

The minute hand of the clock completes the circle every hour and the hour hand completes the circle every 12 hours.

Circles completed by hour hand in 12 hrs = 1

Circles completed by hour hand in 48 hrs = 4

The radius of the circle formed by the short arm is 5cm

For one complete circle, the distance covered is 360° or 2π radian

For 4 circles, the distance covered will be = 4 x 360°  or 4 x 2π radian

                                                                      =  1440°   or  8π radian

Therefore, the distance covered by the short arm in 48 hours is 1440° or  8π radian.