WEBVTT
00:00:00.490 --> 00:00:04.620
A car takes some time to travel from one end of a stretch of road to the other end.
00:00:05.060 --> 00:00:07.890
And the ends of the road are 540 metres apart.
00:00:08.800 --> 00:00:13.270
The car travels along the stretch of road at a constant speed of 36 metres per second.
00:00:14.390 --> 00:00:17.140
How much time does it take for the car to reach the other end?
00:00:18.100 --> 00:00:21.700
So let’s start by underlining all the important information we’ve been given here.
00:00:22.600 --> 00:00:28.460
We know that a car is travelling along the road and the ends of the road are 540 metres apart from each other.
00:00:29.030 --> 00:00:31.830
In other words, the car is travelling 540 metres.
00:00:32.730 --> 00:00:38.790
Whilst it is travelling this 540 metres, the car is moving at a constant speed of 36 metres per second.
00:00:39.790 --> 00:00:45.020
What we’re asked to do is to find out how much time it takes the car to go from one end of the road to the other.
00:00:45.990 --> 00:00:49.110
Now, the first thing we can do is to label all the quantities we’ve been given.
00:00:49.560 --> 00:00:53.130
The distance travelled is 𝑑, which is 540 metres.
00:00:53.160 --> 00:00:55.460
The speed is 𝑠, 36 metres per second.
00:00:55.810 --> 00:00:57.450
And we’re asked to find the time 𝑡.
00:00:58.680 --> 00:01:03.010
To answer this question, we can recall that speed is defined as the rate of change of distance.
00:01:03.870 --> 00:01:16.390
In other words, speed is equal to distance over time or speed is the amount of distance travelled in every unit of time, which means that all we need to do is to take this equation and rearrange it to solve for the time.
00:01:17.190 --> 00:01:18.540
So let’s do that.
00:01:19.500 --> 00:01:28.040
If we multiply both sides of the equation by the time divided by the speed, then we get that the time taken is equal to the distance divided by the speed.
00:01:28.980 --> 00:01:33.950
All we need to do now is to plug in our values and that gives us a time of 15 seconds.
00:01:34.560 --> 00:01:42.050
Therefore, a car travelling 540 metres at a speed of 36 metres per second takes 15 seconds to get there.