@pinkamh It's mainly just a concept. At the beginning, he stated that the initial velocity of the rock was positive in the upward direction. So it makes sense to make something in the downward direction negative.
I had a similar question and was stuck. The question is as such; a stone is thrown (in projectile motion) with vertical speed u from a cliff of 30m high. it hits the ground(bottom of cliff) 5s later. What is the value of u? the solution to this problem includes taking s as -30 in s=ut+1/2at^2. the value of u was found straight forward. What is the logic behind. I dont understand that, help please.
For the finding the max height, if you use the equation V2 squared = v1 squared + 2a(delta)d.
And the projectile was launched at an angle that is NOT 45 degrees. Would you use V1 or V1y?
boohalala 6 days ago
could someone tell me why did the (Vy)f turn out to be -81.9 ??
how can it be negative if we got it from a square root ??
see it at (2min:20sec )
pinkamh 1 month ago
@pinkamh It's mainly just a concept. At the beginning, he stated that the initial velocity of the rock was positive in the upward direction. So it makes sense to make something in the downward direction negative.
yomommasson111 3 weeks ago
@yomommasson111 thanks :)
pinkamh 3 weeks ago
I had a similar question and was stuck. The question is as such; a stone is thrown (in projectile motion) with vertical speed u from a cliff of 30m high. it hits the ground(bottom of cliff) 5s later. What is the value of u? the solution to this problem includes taking s as -30 in s=ut+1/2at^2. the value of u was found straight forward. What is the logic behind. I dont understand that, help please.
prandtl002 3 months ago
Excellent video.
Thank you for such graphical and thorough explanation.
Rosanella :)
lillyvalleys 4 months ago