Video Transcript
A body, moving in a straight line, travelled 91 metres at eight metres per second. Following this, it travelled at 11 metres per second in the same direction for a further 13 seconds. Find the average velocity during the whole trip.
In order to solve this problem, we will use the equation that the velocity is equal to the distance divided by the time. In the first part of the journey, the velocity was eight metres per second. The distance was 91 metres. At present, we don’t know the time. The time can be calculated by dividing the distance by the velocity — in this case, dividing 91 by eight. This gives us 11.375. Therefore, the time taken for the first part of the journey was 11.375 seconds.
For the second part of the journey, we know that the velocity was 11 metres per second. The time was 13 seconds. This time we don’t know the distance. Rearranging the formula in this case gives us that the distance is equal to the velocity multiplied by the time. 11 multiplied by 13 is 143. Therefore, the distance travelled in the second part of the journey is 143 metres.
The question asked us to calculate the average velocity. This can be calculated by dividing the total distance by the total time. The total distance is 234 metres as 91 plus 143 is 234. The total time is 24.375 seconds as 13 plus 11.375 is equal to 24.375. 234 divided by 24.375 is equal to 9.6. Therefore, the average velocity during the whole trip is 9.6 metres per second.
