Question

A train travels at a constant rate of 25 meters per second. How many kilometres does it travels in 5 minutes?(1 kilometres =1000 meters)
A. 6
B. 8
C. 7.75
D. 7.5

Answer 1

Hint: In this question, the first thing that you should do is to write down the formula for finding time and distance. Its formula is $ Time = \dfrac{{Dis\tan ce}}{{Speed}} $ , where time = time taken by object, distance= distance travels by object and speed= in which speed object moves. Firstly we get distance in meters because speed in m/s and then convert in km. Finally put the value in the formula to get the answer.

Complete step-by-step answer:
In this question, it is given that:
Speed =25 $ \dfrac{m}{s} $ and time=5 minutes
We have to find how many distances travelled by the train in 5 minutes.
We know that,
$ Time = $ $ \dfrac{{Dis\tan ce}}{{speed}} $
Put the given value in the above equation, we get;
Firstly we change 5 minutes in second, because speed in m/s.
5 min = 5 $ \times $ 60 sec
$ 5\min t = \dfrac{{Dis\tan ce}}{{25m/s}} $
\[ \Rightarrow 5 \times 60\]Sec =\[\dfrac{{Dis\tan ce}}{{25m/s}}\]
Distance $ = 25 \times 5 \times 60 $ $ m $
$ = 7500 $ $ m $
$ = $ $ \dfrac{{7500}}{{1000}} $ Km
$ = $ 7.5 km
Hence, actual distance travel by train is 7.5 km or 7500 m. So option D is correct.

Note:In this type of question, you should know the formula of time and distance. You can also use the formula for change $ \dfrac{{km}}{h} $ to $ \dfrac{m}{s} $ is $ 1\dfrac{{km}}{h} = \dfrac{5}{{18}}\dfrac{m}{s} $ , also $ 1\dfrac{m}{s} = \dfrac{{18}}{5}\dfrac{{km}}{h} $ . 1hr =60mint and 1mint=60sec. Also where the speed is changing from one value to another the distance also changes. We can say that, Distance =time $ \times $ speed. If distance is constant and speed increases then time decreases also if time increases then speed decreases.