Question

A car moves at a speed of 72 km/hr. what is the speed of the car in metres per second​

Answer 1

Answer:

20 m/s

Step-by-step explanation:

72 km/hr

= (72×1000) m/hr [As 1 km = 1000 m]

= {(72×1000) /3600} m/s       [As 1 hour = 60 minute, 1 minute = 60 sec.

                                            So, 1 hr = 60*60 sec = 3600 sec]

= 72000/3600 m/s

= 720/36 m/s

= 20 m/s

Answer 2

To convert : speed of car in meters per second.

Given : ​speed of car = $72 km /hr$

Solution :

• As we know , $1\ kilometer = 1000 \ meters$ and

                                $1\ hour = 60 \ minutes \\1 \ minute = 60\ seconds$

                            ∴   $1 \ hour = 3600 \ seconds$

•    ∴  $1 (kilometer/ \ hour) = 1 000 ( meters)/ 3600\ (second )$

• On simplifying we get ,

             $1 (kilometer/ \ hour) = 5( meters)/ 18\ (second )$

• Therefore to convert  $km /hr$ to $m/sec$ we multiply given value of speed by fraction $\frac{5}{18}$ .

              $(72 \times\frac{5}{18})meter/second$   $20 m/sec$

Hence , conversion of $72 km /hr$ is $= 20 m/sec$.