00:01
An object is projected upwards with an initial velocity of v0 meters per second from a point s0 meters above the ground.
00:11
We want to show that the velocity squared is equal to v0 squared minus 19 .6 times the precision s of t minus s0.
00:24
So this is a case of projectile motion with constant acceleration.
00:47
And this projectile motion is only in the y direction.
00:51
So i'm going to neglect all these subscripts for y because we're really dealing with a one -dimensional problem.
00:58
So our acceleration a is constant and is equal to minus the gravitational acceleration g.
01:10
And if i wanted to find the velocity now, what i could do is i could take the acceleration and integrate, giving us now that our velocity will be equal to minus gt plus segment integration constant c.
01:40
And using our initial condition that when t is equal to zero, we have an initial velocity of v0.
01:53
We find that c must therefore be equal to v0, implying that our velocity with constant acceleration along the y -axis will be equal to minus gt plus v0.
02:23
Now let's integrate our expression once more to find the position.
02:28
So s of t will be equal to the integral of v of t dt, giving us minus g2 squared over 2 plus v0 t plus another integration constant c.
02:53
And again, we're going to use our initial conditions to find c.
02:57
So when t is equal to zero, the position s is equal to s0, implying that our integration constant c this time will be equal to s0...