Question

A cheetah runs $900\;m$ in $30\;s$. How fast is it going?

Answer 1

Hint: We know that speed is a physical quantity, which measures how fast or slow an object is moving. We also know that speed is defined as the change in position of an object with respect to its initial position and time.
Formula used:
$s=\dfrac{d}{t}$

Complete answer:
We know that speed is a scalar quantity, which gives the magnitude of the object which is in motion. Also speed is the total distance covered by an object within a duration of time. It is mathematically given as $s=\dfrac{d}{t}$, where, $s$ is the speed of the object due to a distance $d$ in time $t$. The SI unit of speed is generally given as kilometres per hour.
Here, it is given that cheetah covers a distance $d=900\;m$ at time $t=30s$.
Then the speed of the cheetah is given as $s=\dfrac{d}{t}$, then substituting the values, we get
$\implies s=\dfrac{900}{30}=30m/s$
Thus the cheetah runs at a speed of $30m/s$

Additional Information:
There are two types of speed generally, average speed and instantaneous speed. Here we are calculating the average speed as we are taking the given data to be the total distance covered in a total time. The instantaneous speed is the speed which is measured at some given instant during the motion.

Note:
Speed and velocity both measure how fast or slow an object moves. But speed is a scalar quantity that has only magnitude and no direction. While velocity is a vector quantity which has both magnitude and direction. Also, note that the SI unit of speed km/h can be converted into m/s and vice versa.