Question
How far does a car travel in 0.75h if it is moving at a constant speed of 88 km/h?
Answer
The car covers a distance of 66 kilometres (km) or 66000 metres (m).
Explanation
Data: The information from the question
The time by which the car covers that distance is, t = 0.75 hours
We also have a constant speed, s = 88 kilometres per hour (km/h)
Unknown: What we need to find
distance, x = ?
Formula: The equation that will help us solve the problem
Speed (s) = Distance (x) / time (t)
Therefore, we are going to use the formula for speed s=x/t to solve the problem
Don’t forget that the SI unit of distance is in meters. Therefore, we need to convert our final answer into meters.
Solution
Simple Method
We will use substitute our data into the formula to obtain:
x = s x t = 88 km/h x 0.75 h = (88 x 0.75) km = 66 km
By converting the above answer into metres, we will have: x = 66 km = 66 x 1000 m = 66,000 m
Alternative Method (Detail explanation)
From our data, we have time, t equals 0.75 hours
Therefore, if to convert hours into standard international (SI) unit which is second, we will follow the steps below:
Since 1 hour = 1 x 60 x 60 seconds = 3600 seconds
We can now see that
0.75 hours = 0.75 x 60 x 60 seconds = 2700 seconds
Therefore, our time t = 2700 s
Additionally,
The distance from our data is in kilometres per hour. And we need to convert it to a standard international (SI) unit which is metres per second. Thus:
Since 1 km/h = 1 (1000/3600) m/s = 0.2778 m/s
Therefore, 88 km/h = 88 (1000/3600) m/s = 24.44 m/s
Final calculation
Now we can solve the distance by applying the values of our speed and time in m/s and s respectively into our formula (s=x/t).
Therefore,
Since we are looking for x, we can easily make it subject of the formula
x = s x t
This implies
x = 24.44 m/s x 2700 s = 66000 m
Therefore, the distance travelled in meters per second is 66,000 m. And we can also convert it into kilometres by saying that it is (66000 /1000) km to give 66 km.
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