Question

A loaded truck covers $16\,km$ in $25$ minutes. At the same speed, how far can it travel in $5$ hours?

Answer 1

In everyday use and in kinematics, the speed (commonly referred to as v) of an object is the magnitude of the rate of change of its position with time or the magnitude of the change of its position per unit of time; it is thus a scalar quantity. The average speed of an object in an interval of time is the distance travelled by the object divided by the duration of the interval; the instantaneous speed is the limit of the average speed as the duration of the time interval approaches zero.

Complete step by step answer:
Speed has the dimensions of distance divided by time. The SI unit of speed is the metre per second (m/s). For air and marine travel the knot is commonly used. The fastest possible speed at which energy or information can travel, according to special relativity, is the speed of light in a vacuum c is 299792458 metres per second.

Matter cannot quite reach the speed of light, as this would require an infinite amount of energy. In relativity physics, the concept of rapidity replaces the classical idea of speed. At the same speed, if distance is more the time taken will also be more therefore it’s directly proportional.

Let us consider the distance covered as x km, as the unit of time is different so we write it as;
We have to first cover minute into hour
We know that ${\text{60}}\,{\text{minutes = }}1\,{\text{hour}}$
$\Rightarrow {\text{25}}\,{\text{minutes = }}\dfrac{{\text{1}}}{{{\text{60}}}}{{ \times 20}}\,{\text{hour}}$
${\text{Speed of truck = }}\dfrac{{{\text{distance}}\,{\text{travelled}}}}{{{\text{time}}\,{\text{taken}}}}$
${\text{Speed of truck = }}\dfrac{{16\,km}}{{\dfrac{{20}}{{60}}\,\min }} = 48km\,h{r^{ - 1}}$
Hence the distance travelled by truck in 5 hours is given by
${\text{distance = speed} \times time}$
On substituting the values we get
$\therefore {\text{distance }= 48 \times 5 = 240 km}$

Therefore the truck can travel 240 km in 5hrs.

Note: Speed has the dimensions of distance divided by time. The SI unit of speed is the metre per second (m/s), but the most common unit of speed in everyday usage is the kilometre per hour. The average speed of an object in an interval of time is the distance travelled by the object divided by the duration of the interval.