Time and Distance
Math MCQs

Question :    An athlete takes 45 second to complete a race of 600 meter. Find the speed of the athlete in kilometre per hour.

Correct Answer  45 km/h

Solution & Explanation

[Strategy to solve the Question: (1) Calculate the speed in m/s and then change this speed into kilometre per hour. (2) change the distance into km and time into hours and then calculate the speed using these units. This speed will be in the required kilometer per hour]

Given,

Distance = 600 meter

Time = 45 second

Now we know that,

Speed = ^Distance/_Time

Thus, speed of the given athlete

= ^{600 40 meter} /_{45 3 second}

= ⁴⁰/₃ m/s

⇒ Speed = ⁴⁰/₃ 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, 15 m/s

= ^{40 8}/₃ × ^{18 6} /₅ km/h

= 8 × 6 km/h = 48 km/h

Thus, speed of the given athlete = 48 km/h Answer

Second method to calculate the speed in km/h using distance given in meter and time given in second.

Here, given distance = 600 meter

= ⁶⁰⁰ /₁₀₀₀ km

[∵ 1000 meter = 1 km. Thus, 1 meter = ¹ /₁₀₀₀ km]

= ⁶ /₁₀ km

Thus, distance = 0.6 km

And, given time = 45 second

= ⁴⁵ /_{60 × 60} hour

= ⁴⁵/₃₆₀₀ hour

= 0.0125 hour

Thus, time = 0.0125 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

= ^{0.6 km} /_{0.0125 hour} km

= 48 km/h

= 48 kilometer per hour

Thus, speed of the given athlete is 48 km/h Answer

[After observing the result obtained here, it is better to calculate the speed in m/s using the given units and after that change the speed from m/s to the required km/h. The use of the type of method depends upon the situation. ]

Calculation of speed using Unitary Method when time and distance are given

Given, Distance = 600 meter

= ⁶⁰⁰/₁₀₀₀ km

⇒ Distance = 0.6 km

And, Time = 45 second

= ⁴⁵/_{60 × 60} hour

= 0.0125 hour

∵ In 0.0125 hour, the distance covered = 0.6 km

∴ In 1 hour, the distance covered = ^{0.6 km} /_{0.0125 hour}

= 45 km/h

Thus, speed of the given athlete = 45 km/h Answer

Similar Questions

(1) At a certain speed a car covers a distance of 98 km in 2 hours. How much distance will it cover in 3 hour?

(2) At a certain speed a car covers a distance of 76 km in 2 hours. How much distance will it cover in 3 hour?

(3) At a certain speed a car covers a distance of 46 km in 2 hours. How much distance will it cover in 3 hour?

(4) By running at a speed of 7 km/h how much distance a bus will cover in 9 second?

(5) At a certain speed a car covers a distance of 72 km in 2 hours. How much distance will it cover in 3 hour?

(6) Find the distance covered by a moving object in 28 hours if it covers a distance of 90 km in 18 hours.

(7) At a certain speed a car covers a distance of 14 km in 2 hours. How much distance will it cover in 3 hour?

(8) At a certain speed a car covers a distance of 62 km in 2 hours. How much distance will it cover in 3 hour?

(9) At a certain speed a scooty covers a distance of 64 km in 4 hours. How much distance will it cover in 5 hour?

(10) Find the distance covered by a car in 20 hours if it covers a distance of 72 km in 10 hours.