Question : After spotting a deer at a distance of 500 m, a tiger takes 1 minute 05 second to catch the prey. If after spotting the deer, the tiger takes about 15 second in thinking and then starts running, then find the speed of the tiger in kilometre per hour.
Correct Answer 36 km/h
Solution & Explanation
Solution
[Strategy to solve the Question: (1) Calculate the speed in m/s after changing the given time in second and then change this speed into kilometre per hour. (2) change the distance into km and time into minute and second, and then calculate the speed using these units. This speed will be in the required kilometer per hour]
Given,
Distance of the deer from the tiger = 500 meter
Time = 1 minute 05 second
= 1 × 60 second + 5 second
⇒ Time = 65 second
And time taken by the tiger in thinking = 15 second
Thus, actual time of running by the tiger to catch the prey
= Total time – Time taken in thinking
= 65 second – 15 second = 50 second
Thus, actual time of running by the tiger = 50 second
Now we know that,
Speed = Distance/Time
Thus, speed of the given athlete
= 500 meter /50 second
= 10 meter per second
⇒ Speed = 10 m/s
Conversion of speed from m/s to km/h
To convert meter per second (m/s) to kilometre per hour (km/h) we need to multiply m/s by 18 /5 .
Thus, 10 m/s
= 10 2 × 18 /5 km/h
= 2 × 18 = 36 km/h
Thus, speed of the tiger = 36 km/h Answer
Second method to calculate the speed in km/h using distance given in meter and time given in second.
Distance of deer from the tiger = 500 meter
= 500 /1000 km = 1 km
[∵ 1000 meter = 1 km. Thus, 1 meter = 1 /1000 km]
Thus, distance = 1/2 km
= 0.5 km
Time = 1 minute 05 second
= 1 × 60 second + 5 second
⇒ Time = 65 second
And time taken by the tiger in thinking = 15 second
Thus, actual time of running by the tiger to catch the prey
= Total time – Time taken in thinking
= 65 second – 15 second = 50 second
Thus, actual time of running by the tiger = 50 second
= 50 /60 × 60 hour
= 5/360 72 hour
= 1/72 hour
Calculation of speed in km/h using formula
Now we know that,
Speed = Distance/Time
Thus, the speed of the given athlete in km/h
= 0.5 km /1/72 hour
= 0.5 × 72 km/h = 36 km/h
Thus, speed of the tiger = 36 km/h Answer
Calculation of speed using Unitary Method when time and distance are given
Given, Distance = 500 meter
Time = 1 minute 05 second
= 1 × 60 second + 5 second
⇒ Time = 65 second
And time taken by the tiger in thinking = 15 second
Thus, actual time of running by the tiger to catch the prey
= Total time – Time taken in thinking
= 65 second – 15 second = 50 second
Thus, actual time of running by the tiger = 50 second
∵ In 50 second, the distance covered = 500 meter
∴ In 1 second, the distance covered = 500 meter /500 second
= 10 m/s or 10 meter per second
Conversion of speed from m/s to km/h
To convert meter per second (m/s) to kilometre per hour (km/h) we need to multiply m/s by 18 /5 .
Thus, 10 m/s
= 10 × 18 /5 km/h
= 2 × 18 km/h
= 36 km/h
Thus, speed of the tiger = 36 km/h Answer
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