Question

If the speed of a motorcycle is $ 40 $ Km per hour, how far can it travel in an hour and a quarter?

Answer 1

Hint :Speed is a scalar quantity which can be defined as the total distance covered in a given interval of time. There can be various approaches for these types of questions. You can either use the direct formula or do it by unitary method. Equations of motion can also be used with better understanding.

Complete Step By Step Answer:
This question can be solved using various methods,
First method-
Using the formula
Given that the speed of the motor cycle $ = s = 40km/h $
The time for which the motorcycle is moving or the given time interval
$ \eqalign{
  & = t = {\text{1 hour and quarter}} \cr
  & {\text{ = 1 + }}\dfrac{1}{4}hr \cr
  & = \dfrac{5}{4}hr \cr} $
Using the definition of speed we know that,
 $ speed = \dfrac{{{\text{distance}}}}{{time}} $
Or by rearranging we get
 $ \displaylines{
{\text{distance = speed}} \times {\text{time}} \cr
{\text{ = 40 km/hr }} \times {\text{ }}\dfrac{5}{4}hr \cr
= 10 \times 5km \cr
= 50km \cr} $
Second method-
In 1 hour motorcycle travels $ = 40km $
In $ \dfrac{1}{2}hr $ motorcycle will travel $ = 40 \times \dfrac{1}{2}km = 20km $
In a quarter or $ \dfrac{1}{4}hr $ , the motorcycle will travel $ = 40 \times \dfrac{1}{4}km = 10km $
Therefore, the total distance travelled in 1 hour and quarter will be $ = 40km + 10km = 50km $ .

Note :
Speed can also be defined as the rate at which an object moves from one place to another in a given interval of time. It is a scalar quantity as it can provide us only with the magnitude and do not specify the direction of motion in which the object is moving, The SI unit of speed is $ m/s $ or $ m{s^{ - 1}} $ .
 $ speed = \dfrac{{{\text{distance}}}}{{time}} $
It can either be uniform i.e. the object travels equal distances in equal intervals of time or variable i.e. the object can travel unequal distance in equal interval of time.