00:01
In this exercise we have our equation s equal to a multiplied by cosine of omega t plus delta.
00:14
Now, for part a we need to find the velocity.
00:17
What is the velocity? well, the velocity is the derivative of s.
00:23
So, what do we get? we get a omega multiplied by negative sine of omega t plus delta.
00:36
In other words, negative a omega multiplied by sine of omega t plus delta.
00:50
Perfect.
00:51
Ok, i was saying, s prime is negative a omega multiplied by sine of omega t plus delta.
01:02
Perfect.
01:04
This is our velocity function.
01:08
Now, part b of our exercise.
01:12
When is the velocity zero? well, here we just need to solve the equation a omega sine of omega t plus delta equal to zero.
01:28
This equation here is equivalent to sine of omega t plus delta equal to zero.
01:40
And well, what do we know? we know that sine is equal to zero if and only if omega t plus delta is equal to what? well, if and only if omega t plus delta is equal to zero plus.
02:05
Ok, now we are going to have k pi with k an integer...