Question

How long will an athlete take to run a 300m race if her speed is 36 km per hour?​

Answer 1

♠️Question:

How long will an athlete take to run a 300m race if her speed is 36 km per hour?

♠️Answer:

As, the distance covered is in meters

And, speed is in km/hr

We need to make their units equal.

$↠ \large{ \sf{speed = 36 \: kmh {}^{ - 1}}} \\ \large{ \sf{ = 2\: \: \cancel{36} \times \frac{5}{ \cancel{18}} ms {}^{ - 1} }} \\ \large{ \sf{ = 10 \: m {s}^{ - 1} }}$

➕Alternate method:

$↠ \large{ \sf{1 \: km = 1000 \: m}} \\ ↠\large{ \sf{ 1 \: hr = 3600 \: seconds}} \\ \large{ \sf{so \: 1 \: kmh {}^{ - 1} = \frac{1000}{3600} ms {}^{ - 1} }} \\ \large{ \sf{36 \: kmh {}^{ - 1} = \cancel{ 36 }\times \frac{1000}{ \cancel{3600} \: \: 100} }} \\ \large{ \sf{ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \boxed{ \red{= 10 \: ms {}^{ - 1} }}}}$

↠ Distance covered = 300 m

↠Speed = 10 m/s

✔We know,

$\large{ \sf{ \star{ time \: taken = \frac{distance}{speed} }}} \\ \large{ \sf{ \to \: time \: taken = \frac{300m}{10 \: ms {}^{ - 1} } }} \\ \large{ \sf{ \to \: time \: taken = \boxed{ \green{ 30sec}}}}$

♠️So, Final answer:

$\huge{ \boxed{ \bold{ \red{30 \: sec}}}}$