00:02
Hi, and the function is given as h is equal to minus 4 .9 t squared plus 70 t and we have plus 200 right this we have at just stands for the object's height in meters and t stands for time passed in seconds since it's launch initial height is 200 meters here we have right so if i just graph it here so this is x and y here right so, or this is given as this will be t and y is h here, right? so here we have, let's say, 200, right? so because the coefficient is negative, right? the coefficient of t squared is negative, right? so parabola will open downwards, right? so the parabola is like that, here we have.
00:57
Here's the parabola like this and go like that.
01:02
So the question says that the object side will be 240 meters twice before it hits the ground.
01:09
So here we have 240 right here we have 240 so 240 here it's coming twice here once here once here 240 meters is coming twice once here and once here before it hits the ground right so we need to find out the time basically so this time here t1 we need to find out and this time here we need to find out here right t1 and t2 at which it reaches 240 meters so for that what what i can do here, i just put the height as the height as 240.
01:43
So 240 equals minus 4 .9 t squared plus 70 t plus 200.
01:53
Now sign up here, right? so i just solve for t here basically.
02:00
So i'll get minus 4 .9 t squared plus 70 t, minus 40 is equal to 0...