Question

Convert speed 90kmph in m/s.

Answer 1

$1km$ is equal to $1000m$ and $1hr$ is equal to $60\min$ which is equal to $3600\sec$. So simply by using these relations we can easily convert the units and will get our answer in desired units (provided the relation between units is correct).

Complete step by step solution
Speed: Speed is a scalar quantity simply telling us how fast the object is moving, or it is the rate at which the object covers distance or we can simply say it is the distance covered by the object per unit time.
As speed is a scalar quantity so it does not have directions and it can not be negative.
It’s formula is given by $\dfrac{s}{t}$ (where s is distance travelled and t is the time taken to travel).
To convert the given value of the speed we first have to remember some of the relations.
As we want to convert units $km{h^{ - 1}}$ to $m{s^{ - 1}}$. So we will use the relation between kilometer and meters; hour and seconds.
Now as
$\Rightarrow$ $1km = 1000m$
$\Rightarrow$ $1hr = 60\min$
And
$1\min = 60\sec$
So
$\Rightarrow$ $1hr = 60\min = 60 \times 60\sec = 3600\sec$
Now we have both the relations between kilometer and meters and as well as hour and seconds
So we convert will now convert 90$km{h^{ - 1}}$ to $m{s^{ - 1}}$
Hence
$\Rightarrow$ 90$km{h^{ - 1}}$ is to be converted into $m{s^{ - 1}}$
Using the relation of kilometer and meter and as well as hour and seconds
We can write
$\Rightarrow$ 90km/h$= 90 \times \dfrac{{1000}}{{3600}}$m/s
So
90km/h=25m/s
Or we can write
$\Rightarrow$ $90km{h^{ - 1}} = 25m{s^{ - 1}}$

Note:
Before solving the answer, first of all check both the units and then try to find relation between both the units. Relation will be as a distance unit with other distance units and time unit relation with time unit.