Question

A cyclist travels a distance of 1 km in the first hour, 0.5 km in the second hour and 0.3 km in the third hour. What is the average speed in $\dfrac{{km}}{{hr}}$ and $\dfrac{m}{{\sec }}$ ?

Answer 1

Average speed: The average speed of something is calculated by dividing the total distance travelled by the total time it took to travel that distance.
So, we will apply a mathematical formula for it and keep the given value in the formula.

Complete step by step solution:
Given that,
Distance covered in the first hour is 1 km.
Distance covered in the second hour is 0.5km.
Distance covered in the third hour is 0.3km.
The total distance travelled $= 1{\text{ }}km + 0.5{\text{ }}km + 0.3{\text{ }}km = 1.8{\text{ }}km.$
Total time taken $= 1hr + 1hr + 1hr = 3hr$
Now, $Average{\text{ }}speed = \dfrac{{Total{\text{ }}distance{\text{ }}traveled}}{{Total{\text{ }}time{\text{ }}taken}}$
So, keeping value in it,
$Average{\text{ }}speed = \dfrac{{1.8}}{3}$
$= 0.6km{h^{ - 1}}$
Now let's convert $kmh{r^{ - 1}}$ to $m{\sec ^{ - 1}}$
Since,
We know $1{\text{ }}km = 1000{\text{ }}m$
and $1hr = \left( {60 \times 60} \right)s{\text{ }} = 3600s$
So, $1kmh{r^{ - 1}} = \dfrac{{1000}}{{60 \times 60}}$
Now convert above calculated value:
So, $0.6\dfrac{{km}}{{hr}} = 0.6 \times \dfrac{{1000}}{{3600}}$
$\Rightarrow 0.6 \times \dfrac{{1000}}{{3600}} = \dfrac{{600}}{{3600}}$
$= \dfrac{1}{6}m{s^{ - 1}}$

Note:
Newton's first law asserts that if a body is at rest or moving in a straight path at a constant speed, it will remain at rest or continue to move in a straight line at a constant speed until acted upon by a force. The law of inertia is the name given to this concept. The second law of Newton is a quantitative description of the effects that a force can have on a body's motion. It asserts that the force imposed on a body equals the time rate of change of its momentum in both magnitude and direction. The product of a body's mass and velocity determines its momentum.