Time and Distance - Arithmetic
Solved Examples-4
Conversion of speed from kilometre per hour to meter per second
p kilometer per hour = how much meter per second?
Solution
Step: (1) convert the kilometer to meter
(1 kilometer = 1000 meter)
Thus, p kilometer per hour = p × 1000 meter per hour
Step: (2) Covert hour to second
(1 hour = 60 minute and 1 minute = 60 second; thus 1 hour = 60 × 60 = 3600 second)
Thus, p × 1000 meter per hour = p × 1000 meter per 3600 second
Step: (3) Calculate the speed for 1 second
∵ In 3600 second the speed = p × 1000 meter
∴ In 1 second the speed
Thus, p kilometer per hour
Thus, to covert the speed from kilometer per hour to meter per second, you need to multiply it by 5/18
Conversion of kilometer per hour to meter per second
Multiple Choice Questions
Choose the correct option
Question (1) If a cyclist is running with a speed of 18 kilometer per hour, what will be his speed in meter per second?
(a) 10 m/s
(b) 5 m/s
(c) 15 m/s
(d) 18 m/s
Answer : (b) 5 m/s
Solution
Given, speed = 18 kilometer per hour
Thus, speed in meter per second = ?
18 kilometer = 18 × 1000 meter = 18000 meter
And, 1 hour = 3600 second
Thus, 1 second
Thus, 18 kilometer per hour
= 5 m/s or 5 meter per second
Thus, option (b) 5 m/s is the correct Answer
Shortcut Method to change kilometer per hour to meter per second
Given, 18 kilometer per hour
We know that to change kilometre per hour to meter per second, we need to multiply with
Thus, 18 kilometer per hour
Thus, option (b) 5 m/s is the correct Answer
Question (2) If a motorcycle is running with 36 kilometer per hour, then what will be its speed in meter per second?
(a) 10 m/s
(b) 5 m/s
(c) 18 m/s
(d) 36 m/s
Answer : (a) 10 m/s
Solution
Given, speed = 36 kilometer per hour
Thus, speed in meter per second = ?
36 kilometer = 36 × 1000 meter = 36000 meter
And, 1 hour = 3600 second
Thus, 1 second = 1/3600 hour
Thus, 36 kilometer per hour
= 10 m/s or 10 meter per second
Thus, option (a) 10 m/s is the correct Answer
Shortcut Method to change kilometer per hour to meter per second
Given, 36 kilometer per hour
We know that to change kilometer per hour to meter per second, we need to multiply with 5/18
Thus, 36 kilometer per hour
Thus, option (a) 10 m/s is the correct Answer
Question (3) If a car is running with a speed of 45 kilometer per hour, then calculate its speed in meter per second.
(a) 10.5 m/s
(b) 5.5 m/s
(c) 12.5 m/s
(d) 10.5 m/s
Answer: (c) 12.5 m/s
Solution
Given, speed = 45 kilometer per hour
Thus, speed in meter per second = ?
45 kilometer = 45 × 1000 meter = 45000 meter
And, 1 hour = 3600 second
Thus, 1 second = 1/3600 hour
Thus, 45 kilometer per hour
= 12.5 m/s or 12.5 meter per second
Thus, option (c) 12.5 m/s is the correct Answer
Shortcut Method to change kilometer per hour to meter per second
Given, 45 kilometer per hour
We know that to change kilometer per hour to meter per second, we need to multiply with 5/18
Thus, 45 kilometer per hour
Thus, option (c) 12.5 m/s is the correct Answer
Question (4) If a car is running with a speed of 54 kilometer per hour, then calculate its speed in meter per second.
(a) 10 m/s
(b) 15 m/s
(c) 20 m/s
(d) 25 m/s
Answer: (b) 15 m/s
Solution
Given, speed = 54 kilometer per hour
Thus, speed in meter per second = ?
54 kilometer = 54 × 1000 meter = 54000 meter
And, 1 hour = 3600 second
Thus, 1 second = 1/3600 hour
Thus, 54 kilometer per hour
= 3 × 5 m/s
= 15 m/s or 15 meter per second
Thus, option (b) 15 m/s is the correct Answer
Shortcut Method to change kilometer per hour to meter per second
Given, 54 kilometer per hour
We know that to change kilometer per hour to meter per second, we need to multiply with 5/18
Thus, 54 kilometer per hour
= 15 m/s or 15 meter per second
Thus, option (b) 15 m/s is the correct Answer
Question (5) A motor car is running with a speed of 63 km/h. What will be its speed in meter per second?
(a) 12.5 m/s
(b) 15.7 m/s
(c) 17.5 m/s
(d) 15.5 m/s
Answer: (c) 17.5 m/s
Solution
Given, speed = 63 kilometer per hour
Thus, speed in meter per second = ?
63 kilometer = 63 × 1000 meter = 63000 meter
And, 1 hour = 3600 second
Thus, 1 second = 1/3600 hour
Thus, 63 kilometer per hour
= 17.5 m/s or 17.5 meter per second
Thus, option (c) 17.5 m/s is the correct Answer
Shortcut Method to change kilometer per hour to meter per second
Given, 63 kilometer per hour
We know that to change kilometer per hour to meter per second, we need to multiply with 5/18
Thus, 63 kilometer per hour
Thus, option (c) 17.5 m/s is the correct Answer
Question (6) If a car is running with a speed of 72 kilometer per hour, then calculate its speed in meter per second.
(a) 10 m/s
(b) 15 m/s
(c) 20 m/s
(d) 25 m/s
Answer: (c) 20 m/s
Solution
Given, speed = 72 kilometer per hour
Thus, speed in meter per second = ?
72 kilometer = 72 × 1000 meter = 72000 meter
And, 1 hour = 3600 second
Thus, 1 second = 1/3600 hour
Thus, 72 kilometer per hour
= 2 × 10 m/s
= 20 m/s or 20 meter per second
Thus, option (c) 20 m/s is the correct Answer
Shortcut Method to change kilometer per hour to meter per second
Given, 72 kilometer per hour
We know that to change kilometer per hour to meter per second, we need to multiply with 5/18
Thus, 72 kilometer per hour
= 20 m/s or 20 meter per second
Thus, option (c) 20 m/s is the correct Answer
Question (7) A motor car is running with a speed of 81 km/h. What will be its speed in meter per second?
(a) 12.5 m/s
(b) 18.7 m/s
(c) 22.5 m/s
(d) 22.7 m/s
Answer: (c) 22.5 m/s
Solution
Given, speed = 81 kilometer per hour
Thus, speed in meter per second = ?
81 kilometer = 81 × 1000 meter = 81000 meter
And, 1 hour = 3600 second
Thus, 1 second = 1/3600 hour
Thus, 81 kilometer per hour
= 22.5 m/s or 22.5 meter per second
Thus, option (c) 22.5 m/s is the correct Answer
Shortcut Method to change kilometer per hour to meter per second
Given, 81 kilometer per hour
We know that to change kilometer per hour to meter per second, we need to multiply with 5/18
Thus, 81 kilometer per hour
Thus, option (c) 22.5 m/s is the correct Answer
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