Question

A car travelled 280 km in 7 hours. What is the speed of the car?

Answer 1

Hint: Required values are given to find out the speed of the car, its distance and time. Dividing the value of distance by the value of time, speed can be found out.

Complete step-by-step answer:
Speed of any body is the measure of distance it can travel per hour or per second. In the question, we are given distance as well as the time in kilometers an hour respectively.
Speed is the ratio of distance travelled to the time taken to cover that distance:
$$\text{Speed = }{\displaystyle \frac{\text{Distance travelled}}{\text{Total time taken}}}$$
Speed can be measured in kilometers per hour (km/hr.), meters per second (m/sec), miles per second or per hour (miles/s, miles/hr.) etc.
Depending upon the unit given in the question, we can find out the speed of the car in any of the units given above.
Here, the distance covered by car is given in kilometers, distance = 280km.
Time taken to cover 280km is given in hours, total time = 7 hours.
According to these given units, we can find out the speed of a car in kilometers per hour (km/hr.)
So,
$$\begin{array}{rl}& \text{Speed = }{\displaystyle \frac{\text{Distance travelled(km)}}{\text{Total time taken(hr)}}}\\ & \Rightarrow {\displaystyle \frac{280km}{7hr}}\end{array}$$
$$\Rightarrow 40{\displaystyle \frac{km}{hr}}$$

Therefore, the speed of the car is 40km/hr.

Note: The question, does not ask to calculate the speed in any other units. If it was asked that, speed should be in meter per second (m/s) rather than km/hr. Conversion could be done as:
$$\begin{array}{rl}& {\displaystyle \frac{40km}{hr}}\Rightarrow 1km=1000\text{ meters and 1 hour = 60}\times \text{60 seconds}\\ & \Rightarrow {\displaystyle \frac{40\times 1000}{60\times 60}}{\displaystyle \frac{m}{s}}=40\times {\displaystyle \frac{10m}{36s}}=40\times {\displaystyle \frac{5m}{18s}}\\ & \Rightarrow 40km/hr={\displaystyle \frac{100}{9}}m/s\end{array}$$