Question

A car travels a distance of 270 km in $ 4\dfrac{1}{2} $ hours. Find its speed.

Answer 1

Hint: The distance covered and the time taken to cover the distance is given, these can be substituted in the formula of speed for its calculation.
Formula of speed:
 $ S = \dfrac{D}{T} $ where,
S = Speed
D = Distance
T = Time

Complete step-by-step answer:
Distance travelled by the car (D) = 270 km
Time taken by the car (T) = $ 4\dfrac{1}{2} $ hours
Converting an improper fraction:
 $ 4\dfrac{1}{2} = \dfrac{9}{2} $
Time taken by the car = $ \dfrac{9}{2} $ hours
Now, speed can be calculated by dividing the distance travelled by time taken:
 $ S = \dfrac{D}{T} $
Substituting the values, we get:
 $
\Rightarrow S = \dfrac{{270}}{{\left( {\dfrac{9}{2}} \right)}} \\
\Rightarrow S = \dfrac{{270 \times 2}}{9} \\
  $
S = 60
A the distance is in kilometers and time in hours, the speed will be in km/h
S = 60 km/h
Therefore, the speed of the given car is 60 km/h.

Note: We can convert a mixed fraction to an improper fraction as:
 $ a\dfrac{b}{c} = \dfrac{{a \times c + b}}{c} $
Speed is a scalar quantity whose SI unit is m/s.
Dimensional formula of speed is $ {M^0}{L^1}{T^{ - 1}} $
In vehicles, we use speedometers to measure the speed and odometers to measure the distance.
Speed can be uniform and variable depending upon the distance covered in intervals.
If equal distance is covered in equal intervals of time then the speed is uniforms and if different distances are covered in equal intervals of time then the speed is variable (varies with respect to time)