Video Transcript
What is the speed of an object that
travels a distance of 300 meters in a time of 25 seconds?
So in this case, we’ve got an
object, which we’ll say for the purpose of our question is this round blobby
thing. And we’ve been told that the object
moves 300 meters. So let’s say it moves 300 meters in
this direction, which means that it starts here and finishes here. And we’ve been told that it travels
a distance of 300 meters in a time of 25 seconds. We need to work out the speed of
this subject. So let’s start by providing labels
to the 300 meters and 25 seconds.
Let’s say that the distance moved
firstly is called 𝑑 and the time taken to travel that distance is called 𝑡. Then, we can recall the definition
of speed. Speed is the rate of change of
distance moved by an object. In other words, speed is equal to
the distance moved by an object divided by the time taken to travel that
distance.
And in this question, we’ve already
been given the distance travelled by the object and the time taken to travel that
distance. So we can work out the speed simply
by substituting in our values of 𝑑 and 𝑡. So we can say that the speed of the
object 𝑠 is equal to 300 meters — that’s the distance moved by the object — divided
by 25 seconds — that’s the time taken for the object to move 300 meters.
And since we’ve kept our units in
the calculation, we can see that our final answer is going to have the unit of
meters per second or meters divided by seconds. And so, when we evaluate the
right-hand side of this equation, we get our final answer which is that the speed of
the object is 12 meters per second.
In other words, every second that
object is travelling 12 meters. So the first second it travels 12
meters, the second second it travels another 12 meters, the third second it travels
yet another 12 meters, and so on and so forth until 25 seconds later and it’s
traveled the total distance of 300 meters. Hence, we say that it’s done this
at a speed of 12 meters per second.
