# A long distance runner is running at a constant speed of 5 m/s.

## Question

A long distance runner is running at a constant speed of 5 m/s. How long does it take the runner to travel 1 km.

It will take the runner 200 s to travel 1 km.

## Explanation

Data: The information from the question

The runner has a constant speed, s = 5 m/s

Distance covered by the runner, x = 1 km

By converting kilometre to metre, we will have our distance (x) as:

1 km = 1000 m

Thus, distance, x = 1000 m

Unknown: The information we need to find from the question

The time it takes the runner to travel 1 km, t = ?

Formula: The equation that will help us to solve the problem

We already know that speed (s) = distance (x) / time (t)

Since we are looking for time, we will make t subject of the formula:

t = x / s [This is the equation that will help us to solve the problem]

### Solution

First (simple) Method: In second

Applying t=x/s, we will have:

Time, t = x / s = 1000 m / 5 ms-1 = 200 s

Therefore, it will take the runner 200 seconds to travel 1 kilometre. A long distance runner is running at a constant speed of 5 m/s. How long does it

Second (alternative) Method: In hour

Since we already have our distance x = 1 km

Our speed, s = 5 m/s

We can convert the above speed into kilometres per hour (km/h) by following the method below:

Since the speed s = 5 m/s and 1 m/s = 3.6 km/h

We can equally say that s = 5 m/s = 5 (3.6 km/h) = 18 km/h

In kilometres, the speed, s = 18 kilometres per hour

Now, to find time, t = x / s = (1 km) / (18 kmh-1) = 0.06 hours.

Therefore, it will take the runner 0.06 hours to travel 1 km.

Check University Physics and Fundamentals of Physics for more examples.

You may also like to read:

What is Speed in Physics