00:01
Let's say we have a car that accelerates to a speed of 10 meters a second, and it does so in a time interval of 5 seconds.
00:09
Sorry, it goes from an initial speed of 10 to a final speed of 30.
00:13
Let me correct that.
00:14
Then the acceleration is just going to be the change in velocity over the time interval.
00:19
That's a change of 20 meters a second over 5 seconds.
00:24
That's 4 meters per second squared.
00:28
Squared.
00:28
For the second one, we have a bus moving at 20 meters a second when it slows down with an acceleration of negative 5 meters a second squared.
00:39
And this is over the interval, or sorry, we want to know how long does it take to come to a stop, or how far does it come to a stop.
00:46
So we'll call that distance x.
00:48
This is basically just going to be v squared over 2a with a negative sign.
00:53
Alright, so let's say, so that should be 40 meters.
00:57
For problem three, we have a block sliding down a plank that has a length of 18 meters, and it has an acceleration of 4 meters a second squared, so we want to know how long does it take to reach the bottom...